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Structure and performance of LiFePO4 cathode materials A review

Journal of Power Sources 196 (2011) 2962–2970

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Journal of Power

Sources

j o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /j p o w s o u

Review

Structure and performance of LiFePO 4cathode materials:A review

Wei-Jun Zhang

Department of Mechanical Engineering,Virginia Commonwealth University,401West Main Street,Richmond,VA 23284,United States

a r t i c l e i n f o Article history:

Received 1October 2010Received in revised form 12November 2010

Accepted 22November 2010

Available online 26 November 2010Keywords:Battery LiFePO 4

Performance

Reaction mechanism Carbon coating

a b s t r a c t

LiFePO 4has been considered a promising battery material in electric vehicles.However,there are still a number of technical challenges to overcome before its wide-spread applications.In this article,the structure and electrochemical performance of LiFePO 4are reviewed in light of the major technical requirements for EV batteries.The rate capability,capacity density,cyclic life and low-temperature per-formance of various LiFePO 4materials are described.The major factors affecting these properties are discussed,which include particle size,doping,carbon coating,conductive carbon loading and synthesis techniques.Important future research for science and engineering is suggested.

Contents 1.Introduction..........................................................................................................................................29622.

Lithium insertion/extraction mechanism ...........................................................................................................29632.1.Crystal structure..............................................................................................................................29632.2.Phase transformation.........................................................................................................................29643.

Electrochemical performance........................................................................................................................29643.1.Rate capability................................................................................................................................29643.2.Capacity density..............................................................................................................................29643.3.Cyclic and calendar life.......................................................................................................................29653.4.Temperature dependence....................................................................................................................29664.

Factors affecting performance and energy cost .....................................................................................................29664.1.Particle size...................................................................................................................................29664.2.Doping........................................................................................................................................29674.3.Carbon coating................................................................................................................................29674.4.Conductive carbon............................................................................................................................29674.5.Synthesis methods ...........................................................................................................................29685.Future research needs................................................................................................................................29686.

Conclusions ..........................................................................................................................................2968Acknowledgements..................................................................................................................................2968References . (2968)

1.Introduction

LiFePO 4has been selected as one of the primary battery mate-rials for electric vehicle (EV)applications [1].The main advantages of LiFePO 4are its ?at voltage pro?le,low material cost,abundant material supply and better environmental compatibility compared

E-mail address:zweijun@https://www.sodocs.net/doc/544601632.html,

to other cathode materials [3–8].The drawbacks of LiFePO 4include its relatively low theoretical capacity,low density,poor electronic conductivity and low ionic diffusivity (Table 1).Moreover,the pro-cessing cost of LiFePO 4is generally high because carbon coating or small particle size is required to obtain appropriate performance at high current rates.

Since its discovery in 1997[9],great progress has been made in improving and understanding the structure,electrochemical per-formance and synthesis techniques of LiFePO 4[10–161].These

W.-J.Zhang/Journal of Power Sources196 (2011) 2962–29702963

Table1

Comparison of the properties of different cathodes in18,650cells[2].

Property LiAl0.05Co0.15Ni0.8O2LiCoO2LiMn2O4LiFePO4

Avg.voltage(V) 3.65 3.84 3.86 3.22 Theo.capacity(mAh g?1)265274117170

True density(g cm?3) 4.73 5.05 4.15 3.60 Speci?c energy(Wh kg?1)219.8193.3154.3162.9 Energy density(Wh L?1)598.9557.8418.6415.0 Materials’cost 1.628 1.824 1.159 1.219 Energy cost(Wh US$?1) 6.08 5.05 5.97 6.31

Table2

Summary of major requirements for HEV and PHEV batteries[1].

Characteristics HEV PHEV(10miles)PHEV(40miles)

Pulse discharge power(kW10s?1)25–403846

Available energy(kWh)0.3–0.5 3.411.6

Cycle life(charge sustaining,50Wh)300,000300,000300,000

Cycle life(charge depleting)N/A50005000

Calendar life(years)1515(35?C)15(35?C)

Maximum weight(kg)40–6060120

Maximum volume(L)32–454080

Max.price($)(100k units year?1)500–80017003400

Operating temperature(?C)?30to+52?0to+52?30to+52

advances have been discussed in several elegant review articles [5–8].The current work attempts to provide a brief overview of the major achievements and the remaining challenges related to EV applications.A realistic understanding of the promises and concerns of LiFePO4is important to the massive adoption of this material in the EV market.

According to the standard proposed by the US Department of Energy(Table2),the major technical barriers that need to be addressed for the commercialization of high-energy batter-ies for PHEVs(plug-in hybrid electric vehicles)and high-power batteries for HEVs(hybrid electrical vehicles)are as follows [1]:

(1)Performance.Much higher energy densities are required to meet

the volume/weight requirements;the cyclic stability and low-temperature performance must be improved.

(2)Cost.The current cost of the promising Li-ion batteries is

approximately two to?ve times too high on a kWh basis due to the high cost of raw materials,cell packaging and manufac-turing process.

(3)Life.A long calendar life of15years for both PHEV and HEV is

anticipated to be dif?cult to achieve.Speci?cally,the impact of combined EV/HEV cycles and extended time in a high state of charge on the battery life is unknown.

(4)Abuse tolerance.Tolerance of abusive conditions must be

addressed,such as short circuit,overcharge,over-discharge, and exposure to?re.

In this article,the current status of LiFePO4research is reviewed in light of these technical challenges.The paper starts with a brief summary on the Li insertion/extraction mechanism,discusses the electrochemical performance in terms of rate capability,capacity density,cyclic stability and low-temperature behavior,and then describes the major performance-controlling factors and future research needs.

2.Lithium insertion/extraction mechanism

2.1.Crystal structure

The triphylite LiFePO4belongs to the olivine family of lithium ortho-phosphates with an orthorhombic lattice structure in the space group Pnma[9–12].The lattice parameters are a=10.33?A, b=6.01?A,c=4.69?A and V=291.2A3.The structure consists of corner-shared FeO6octahedra and edge-shared LiO6octahedra running parallel to the b-axis,which are linked together by the PO4tetrahedra(Fig.1).Upon delithiation,the Li ions are extracted to yield heterosite FePO4without changing the olivine framework [9,13].However,the lattice constants are changed to a=9.81?A, b=5.79?A,c=4.78?A and V=271.5A3for FePO4,which corresponds to a reduction in lattice volume by6.77%,an increase in c by1.9%, and a decrease in a and b by5%and3.7%,respectively.

Because the oxygen atoms are strongly bonded by both Fe and P atoms,the structure of LiFePO4is more stable at high tempera-tures than layered oxides such as LiCoO2.LiFePO4is stable up to 400?C,while LiCoO2starts to decompose at250?C[14–16].The high lattice stability results in excellent cyclic performance and operation safety for LiFePO4.However,the strong covalent oxygen bonds also lead to low ionic diffusivity(10?13to10?16cm2s?1)and poor electronic conductivity(～10?9cm s?1)[17].The Li diffusion in FePO4is widely believed to be one dimensional along the b-axis [10,11,18]

Fig.1.The crystal structure of LiFePO4viewed along the c-axis[12].The Fe atoms occupy octahedral(4c)sites(dark shading)and the P atoms occupy tetrahedral (4c)sites(light shading).The Li ions(small circles)occupy octahedral(4a)sites. Reproduced with permission from Elsevier.

2964W.-J.Zhang/Journal of Power Sources196 (2011) 2962–2970

2.2.Phase transformation

According to classical theory,the driving force for atom diffusion in a single phase is the concentration gradient.A higher concen-tration gradient results in fast atom diffusion.Unfortunately,such concentration gradients are rare in microsized Li x FePO4particles due to the very limited solid-solution range for both LiFePO4and FePO4phases[19–21].The solubility is believed to be less than0.05 at room temperature for particles larger than100nm.At high tem-peratures,the miscibility gap between these two phases decreases [22,23].The transformation from heterosite and triphylite phases to a disordered solid solution of Li x FePO4takes place at approximately 200?C.These two phases are entirely soluble at temperatures above 300?C.Note that the phase diagram strongly depends on the par-ticle size due to the surface energy effect[24,25].The miscibility gap between LiFePO4and FePO4contracts when the particle sizes are reduced to less than50nm,and a completely solid solution is predicted for particles smaller than15nm at room temperature [26].

The phase transformation during Li insertion/extraction was ini-tially proposed to follow the core–shell model or mosaic model [9,12].According to these models,the shell of one phase cov-ers the core of a second phase and the diffusion occurs through the shell with the movement of the interface.These models have been questioned based on the?ndings that the partially delithiated LiFePO4particles contain several FePO4domains and that the inter-facial zones are not a solid solution but the superposition of two end phases[27–29].Based on these observations,alternative mod-els have been proposed including the“spinodal-decomposition model”[29]and the“domino-cascade model”[30].Both mod-els suggest that the Li insertion/extraction processes involve the cooperative motion of Li ions along the b-channels through the movement of phase boundaries(the nucleation front).Because the process is not diffusion-controlled in nature,no solid solution zones are required.

The mechanism proposed in these two models agrees well with the kinetic analysis of the process which indicates that the phase transformation is a phase-boundary controlled,one-dimensional process[31].However,the main difference between these two models is the motion speed of the phase boundaries.The domino-cascade model claimed that the speed is extremely high so that no particles with the mixing phases are identi?ed in the reaction pro-cess,therefore,the individual particles are either single triplylite or single heterosite[30].The spinodal-decomposition model sug-gests that the movement of phase boundaries is relatively slow, and multiple domains and phase interfaces can be observed in the partially delithiated particles,as shown in Fig.2.Note that the Li insertion/extraction processes in LiFePO4appear to depend on the particle size,synthesis method,surface coating,charging rate and testing procedures[33–36].In nanosized particles,the phase trans-formation may deviate far from the equilibrium prediction for bulk materials because of the pronounced effect of surface and inter-face energies in small particles,which has been observed in Li x TiO2 and alloy anodes[37,38].Therefore,more studies are warranted to understand the Li insertion/extraction mechanism in LiFePO4 under real operation conditions using advanced in situ characteri-zation tools.

3.Electrochemical performance

3.1.Rate capability

The rate capability of LiFePO4has been extensively investigated due to the need for high pulse power in many applications.The rate capacity is affected by many factors,including particle size,

doping,Fig.2.HRTEM image of a partially delithiated LiFePO4particles showing a LiFePO4 domain(LFP)in the ac plane surrounded by FePO4phase(FP)with narrow inter-face layers consisting of two crystal phases[29].Reproduced with permission from Elsevier.

carbon coating,synthesis route,conductive carbon loading and the mixing procedure[39–44].A comprehensive comparison of the rate capacity of various LiFePO4materials has been presented in a previ-ous paper[45].The analysis points out that the electric conductivity between the LiFePO4powders and the current collector plays a crit-ical role in the high-rate performance of the battery cells.Carbon coating seems to improve the rate capacity of LiFePO4more effec-tively than particle size reduction and cation doping.Because the LiFePO4/FePO4reaction is a non-diffusional,cooperative process as discussed above,the transport of Li ions and electrons through the particles is not expected to be the limiting process.Instead,the fast transport of electrons from the particle surface to the current col-lector is more critical,particularly at a high current rate,provided that the diffusion of Li-ions through the electrolyte to the graphite anode is not limited.Thus,carbon coating and conductive carbon loading are more likely to be important than particle size control and doping at high current rates.

As shown in Fig.3,the materials prepared by polyol,direct-precipitation,sol–gel and ball-milling exhibit excellent high-rate capacities[45].The microsized particles(DP-140,BM-C-300) exhibit excellent high-rate capacities,which are comparable to that of the best nanosized sample(PL-30).It is interesting to note the exceptional high-rate performance of the SS-50material in Fig.3, although the result was disputed by others[46,47].This material is a non-stoichiometric LiFePO4prepared by a solid-state reaction (ball milling)and tested in a half cell using Li-metal as the anode. The superior performance of this material was attributed by the authors to its small particle size(50nm)and the surface coating of pyrophosphates on the particles[48].It will be interesting to eval-uate this material in a full cell to examine its potential for practical application and to identify the impact of graphite anode on the rate performance of LiFePO4/graphite full cell.

3.2.Capacity density

The speci?c energy(Wh kg?1)and energy density(Wh L?1)of battery cells are important parameters for EV and other appli-cations.Increasing the speci?c energy signi?cantly reduces the battery mass and cost,which are two of the major technical bar-riers to the wide-spread application of Li-ion batteries in EVs.The speci?c energy of battery cells is determined by many factors such as cell design,electrode structure,electrode potential and capacity

W.-J.Zhang /Journal of Power Sources 196 (2011) 2962–2970

2965

90100110120130140150160

1700.1

10100

S p e c i f i c c a p a c i t y (m A h /g )

C-rate

PL-30 (88)DP-140 (42)BM-C-300 (119)SG-C-170 (155)DOP-Cr-C-100 (99)SS-50 (48)

DOP-Nb-100 (40)

https://www.sodocs.net/doc/544601632.html,parison of the rate capacities of LiFePO 4materials prepared by differ-ent synthesis methods or with doping:PL (polyol),DP (direct-precipitation),SG (sol–gel),BM (ball-milling),SS (solid-state reaction)and DOP (doping)[45].These samples represent the best materials from each category reported to date.The par-ticle sizes and carbon coating (C)are indicated in the legend.Reproduced with permission from The Electrochemical Society.

[49,50].Among these,the capacity density (mAh L ?1)of the cathode is one of the most critical factors because the active cathode mate-rials account for approximately 40%by weight of the high-energy cells (Table 3).

The speci?c capacity (mAh g ?1)of LiFePO 4has been widely investigated,and high speci?c capacities close to the theoretical value (170mAh g ?1)are obtained in a number of LiFePO 4materi-als (Fig.3).However,the energy density of battery cells is more correlated to the capacity density than the speci?c capacity.Due to carbon coating and particle size reduction,the tap densities of LiFePO 4powders are generally low compared to those of other cathode materials [44,51,52].For example,the nanosized LiFePO 4materials have a tap density of 0.6–1.0g cm ?3,while the commer-cial LiCoO 2materials have a tap density of approximately 2.6g cm ?3[52,54,92].A low tap density reduces energy density and increases the cell size and cost because more supporting materials such as electrolyte,separator and packaging materials,are needed as a result of less loaded active powders per volume or per area.The supporting materials account for a large portion of the mass and cost of battery cells,as shown in Tables 3and 4.Therefore,high speci?c capacity does not necessarily lead to high energy density for LiFePO 4if its tap density is low.In future studies,it is proba-bly more meaningful to use capacity density,rather than speci?c capacity,to evaluate LiFePO 4materials.

Table 3

Estimated material content of typical Li-ion cells [32].Material/component

High-energy cell (100Ah)High-power cell (10Ah)Quantity (g)

wt.%Quantity (g)wt.%Anode (dry)785235617Cathode (dry)1610479329Active material 1408417423Electrolyte 618184413Separators

60 1.8165Package (other)

358

115

Table 4

The estimated cost of major components in 18,650cells with different cathodes [2].

Component/material LiAl 0.05Co 0.15Ni 0.8O 2LiCoO 2LiMn 2O 4LiFePO 4Cathode 0.5230.7510.1870.213Anode

0.2740.2400.1910.218Electrolyte 0.2670.2960.2960.276Separator 0.1740.1560.1300.140Others 0.3900.3810.3550.372Total

1.628

1.824

1.159

1.219

The tap densities of microsized LiFePO 4are in the range of 1.0–1.5g cm ?3[54–57].New synthesis approaches have been explored recently to increase the tap density by control-ling the morphology and size distribution of LiFePO 4particles [51,54,58,59].A high tap density of 1.8g cm ?3was achieved for a LiFePO 4/C composite containing 7wt.%carbon prepared by a two-step drying process [54].The composite shows a high speci?c capacity of 98mAh g ?1and a high capacity density of 167mAh cm ?3at 5C rate.A LiFePO 4material with a tap den-sity of 1.3g cm ?3exhibits a high speci?c capacity of about 100mAh g ?1at 10C rate [58].When tested in a half-cell at a 30-min charge–discharge rate,excellent speci?c energy (440Wh kg ?1)and power density (900W kg ?1)were obtained although its spe-ci?c capacity is not high compared to the best materials shown in Fig.3.

3.3.Cyclic and calendar life

For batteries in both HEV and PHEV,the required cycle life at charge-sustaining mode (shallow-discharge)is 300,000cycles and the expected calendar life is 15years.In addition,a cycle life of 5000cycles in the charge-depleting mode is required for PHEVs.These requirements are anticipated to be very challenging for any type of Li-ion batteries.For LiFePO 4cathodes,long cyclic lives of 1500–2400cycles have been achieved in laboratory tests [58–62].However,the challenge is to develop adequate testing protocols that can effectively simulate and predict the battery performance in EV services [63].To design appropriate testing procedures,it is necessary to understand the capacity-degradation mechanisms in both cycling (driving)and storage (parking)conditions.

The possible mechanisms of capacity degradation in LiFePO 4cells include the following:(1)loss of Li inventory through a side reaction,(2)loss of active materials due to cracking and disso-lution,(3)the rise of cell impedance due to the formation of SEI (surface–electrolyte-interface)layers,and (4)physical degra-dation of electrode structure [64–69].Among these,the loss of Li-inventory due to SEI formation is considered to be the major cause [70,71].Early studies have indicated that the SEI formation on graphite anode in LiFePO 4cells is catalyzed and destabilized by the iron-deposits migrated from the LiFePO 4cathode through the electrolyte [65,66].Iron precipitates were observed on the surface of the graphite anode and on the separator [66,72,73].The degree of capacity degradation seems to have a direct correlation with the iron content accumulated on the graphite anode [72,74].It is believed that these irons are etched from the active LiFePO 4parti-cles by the acidic electrolyte solution.It was found that replacing the LiPF 6salt with less-acidic LiBOB or LiAlO 4salts in the elec-trolyte leads to much less iron dissolution and,therefore,much better capacity retention [65,75].

The dissolution rate of iron in an electrolyte also depends on the testing temperature,the cut-off voltage,the synthesis method,the impurity content and the particle size of LiFePO 4[65,72–78].Higher temperature,higher cut-off voltage (4.2V),smaller parti-cle size,and the presence of moisture or impurity phases such as Fe 4(P 2O 7)3lead to a higher rate of iron dissolution and faster capac-

2966W.-J.Zhang/Journal of Power Sources

196 (2011) 2962–2970

Fig.4.The temperature dependence of speci?c capacities of LiFePO4materials tested in half-cells with different electrolytes:A:LiClO4/EC-DMC[118],B:LiPF6/EC-DMC[82],C:LiPF6/EC-DMC-DEC-EMC[80],and D:LiBF4–LiBOB/PC-EC-EMC[81].

ity fade.For example,the capacity retention of a LiFePO4/graphite cell dropped from100%to57%after100cycles when the temper-ature was increased from25to37?C[65].Replacing the graphite anode with Li-metal or Li4Ti5O12improved the capacity retention from about30%to90%at55?C after100cycles.The capacity reten-tion can also be improved by coating the graphite anode or LiFePO4 particles with polymer or oxide?lms to retard the iron dissolu-tion and deposition[68,74,79].The dissolution of iron has multiple detrimental effects:catalyzing the SEI formation on anode,reduc-ing the inventory of active materials,and increasing the electric resistance.Mechanical cracking may also lead to the isolation of the active particles from the electrolyte or the conductive networks [67].

3.4.Temperature dependence

The poor performance of Li-ion batteries at low temperature is one of the major technical barriers for EV applications[1].The operating temperature range for EV batteries is?40?C to+50?C. The speci?c capacities of LiFePO4have been observed to decrease rapidly at low temperature(especially below?20?C),as shown in Fig.4.The in?uence of temperature on the capacity is more pronounced at high charge rates.The loss of capacity at low tem-perature has been attributed to the limited electrode kinetics, low electrolyte conductivity,low Li diffusivity,and high charge-transfer resistance at the electrode/electrolyte interface[80–83]. As shown in Fig.4,the low-temperature capacity can be improved by optimizing the Li-salts or the electrolyte solutions(samples C–D vs.A–B).The quaternary carbonate-based electrolyte(sam-ple C)leads to better speci?c capacities at temperatures below ?20?C as compared to the binary electrolyte(samples A and B) [80].The use of mixed LiBF4–LiBOB salts in the electrolyte pro-vides higher capacity over a wide temperature range(?50to 80?C)than LiBF4alone[81].The in?uence of electrolyte formula-tion,carbon coating,particle size and surface structure of LiFePO4 on the low-temperature performance deserves further evalua-tion.The in?uence of low temperature on the cycling stability of LiFePO4has also not been clearly understood yet.A study on a LiFePO4/graphite cell with a polymer-gel electrolyte indicated that the cyclic capacity decreased more rapidly at0?C than at25?C [84].

At high temperatures,the speci?c capacities of LiFePO4are improved due to the increased lithium diffusion rate and elec-tron transfer activity[15,85].However,cycling or storing the LiFePO4cells at high temperature results in signi?cant capacity fade[65,71,83].The cause of capacity fade at elevated temperature has been attributed to the increased dissolution of Fe-ions from LiFePO4particles into the electrolyte,which are then deposited on the graphite anode surface.The deposited iron catalyzes the formation of SEI?lms,leading to an increase of interfacial impedance of graphite electrodes[65].The high temperature sta-bility was improved with a LiBOB electrolyte or Li4Ti5O12anode [34,65].

4.Factors affecting performance and energy cost

The electrochemical performance and energy cost of LiFePO4 batteries are affected by many factors such as the electrolyte,sepa-rator and electrode materials.In this section,the major contributors related to the LiFePO4cathode are discussed.

4.1.Particle size

Particle size reduction has been employed in a number of stud-ies as an effective method to improve the high-rate capacity and cycling stability of LiFePO4materials[42,48,86–88].The capacities of LiFePO4at high current rates are believed by many to originate from its low ionic conductivity[89].Logically,the high-rate per-formance can be improved by reducing particle size because the transport distance for electrons and Li-ions is thus reduced.In fact, the best high-rate performance for LiFePO4was achieved in the samples with very small particle size(30–50nm),e.g.,PL-30and SS-50in Fig.3.

However,a recent analysis[45]of over40different LiFePO4 materials reported in the literature indicates that the speci?c capac-ity of LiFePO4has no clear dependence on the particle size in the range50–400nm at0.1C and1C rates as shown in Fig.5,which is contrary to a previous analysis[89]which concluded that the capacity of LiFePO4depends solely on the mean particle size.Even at10C rate,the speci?c capacities of microsized LiFePO4samples (200–300nm)with carbon coating are comparable to those of many nanosized samples.The lack of direct correlation between the spe-ci?c capacity and particle size may be related to the cooperative Li-movement process during Li insertion/extraction as discussed above.Because the transport of Li-ions in these particles is not diffusion-controlled,particle size reduction may not lead to as much improvement as expected in the size range of interest.

As mentioned in Section2,the phase transformation in LiFePO4 particles smaller than50nm is likely to be different from that in microsized particles.Thus,it is possible that these particles may exhibit superior capacity at high current rates.However,the capac-ity gain in nanosized LiFePO4materials may be not enough to offset their many adverse effects in real applications,although further research on these tiny particles is of scienti?c signi?cance.The tap densities of nanoparticles are generally low,while their man-ufacturing costs are often high compared to microsized particles, leading to low energy density and high energy cost of the cells. Smaller particles also require more supporting materials such as conductive carbon,binder and current collector in a battery cell [49].Due to their high surface areas and less-coordinated sur-face atoms,nanoparticles are more prone to surface reaction and particle dissolution in electrolyte,which may severely reduce the cyclic and calendar life of battery cells[90].Processing and han-dling of nanoparticles are dif?cult and require extra precaution due to the health and environmental concerns.Therefore,the opti-mum particle size for high-power applications seems to be in the range of200–400nm,as estimated from the data shown in Fig.5.The ideal particle size may be even larger for high-energy applications such as in PHEVs,where the energy density,bat-tery mass and energy cost are more important than the high-rate capacity.

W.-J.Zhang /Journal of Power Sources 196 (2011) 2962–2970

2967

7090

110130150

S p e c i f i c C a p c i t y (m A h g -1)

Particle Size (nm)

110120130140

150160170

S p e c i f i c C a p c i t y (m A h g -1)

130140150160170180

S p e c i f i c c a p a c i t y (m A h /g )

Fig.5.The dependence of speci?c capacity at 0.1C,1C and 10C rates on the particle size of LiFePO 4with or without carbon coating [45].Reproduced with permission from The Electrochemical Society.

4.2.Doping

The positive effect of doping on the rate capacity and cyclic stability of LiFePO 4has been reported in a group of studies [40,91–102].The studied dopants include supervalent cations such as Nb 5+[40],Zr 4+[91],Ti 4+[91],Mo 6+[95],Mg 2+[93,100],Cr 3+[92,99],V 5+[94],Co 2+[96],Cu 2+[97],and anions of Cl ?1[102]and F ?1[101].The promoting effect was attributed to the improved intrinsic electronic conductivity and the increased Li-ion diffusion coef?cient in doped LiFePO 4particles [98–103].The electronic con-ductivity of LiFePO 4powders was reported to increase by two to eight orders of magnitude as a result of doping-induced charge compensation [40,98,100].

However,the improvement in electronic conductivity was questioned by others to arise from the formation of conductive surface ?lms (e.g.,carbon,Fe 2P or Fe 75P 15C 10),as con?rmed by TEM observations [104–106].Modeling studies also suggested that supervalent doping on either Li or Fe sites is energetically unfavor-

able and does not result in a large increase of electronic conductivity [11,107].Neutron and XRD studies revealed that the doped Zr,Nb and Cr atoms in LiFePO 4are located primarily on the Li sites and,thus,may hinder the Li diffusion by blocking the Li-diffusion chan-nels [108].In terms of electrochemical property,the doped LiFePO 4materials do not show signi?cant advantages over the undoped samples [45].For example,the speci?c capacities of the doped sam-ple without carbon coating (DOP-Nb-100)are much lower than those of other materials despite of its small particle size (100nm)(Fig.3).Therefore,doping does not appear to be as effective as carbon coating for engineering applications,especially when tak-ing into account the impact of doping (e.g.,Nb and Mo)on the cost of raw materials.For the anion-doped LiFePO 4(Cl ?1and F ?1)[101,102],the impact of doping on their structural stability and abuse tolerance at high temperature needs to be examined.4.3.Carbon coating

Carbon coating is one of the most important techniques used to improve the speci?c capacity,rate performance and cycling life of LiFePO 4[109–115].The main role of carbon coating is to enhance the surface electronic conductivity of LiFePO 4particles so that the active materials can be fully utilized at high current rates.Carbon coating also reduces the particle size of LiFePO 4by inhibiting par-ticle growth during sintering [116–118].In addition,carbon can act as a reducing agent to suppress the oxidation of Fe 2+to Fe 3+during sintering and thus simplify the atmosphere requirement in synthesis [119,120].With carbon coating,the microsized par-ticles of ～300nm exhibit good rate capability that is comparable to those of the nanosized particles,as shown in Fig.5.The bene?cial effect of carbon coating has been observed to depend on the struc-ture,uniformity,thickness,loading and precursor of the coating [110–112,121–123].The disadvantages of carbon coating include high processing cost and reduced tap density,which may lead to high energy cost and low energy density of the battery cells [44,52].Therefore,it is important to optimize the carbon coating on LiFePO 4to meet the performance and cost targets for EV applications.

Carbon coating on LiFePO 4can be prepared with pre-existing carbon powders or by in situ carbonization of organic precursors [124–129].It is now commonly believed that the carbon coatings formed in situ perform much better than the pre-existing carbons [125].The structure and electronic conductivity of carbon coat-ing produced from organic precursors are strongly in?uenced by the pyrolysis temperature and the precursor type [110,112].Car-bon coatings prepared at high temperature (>700?C)have much higher electronic conductivity than those prepared at low temper-ature (<600?C)as result of the increased amount of graphite carbon in the coating [110,119].Graphite carbons (sp 2-coordinated)are more conductive than disordered carbons (sp 3-coordinated).The amount of graphite carbon in the coating can be determined from the band-intensity ratio of graphite (I G )and disordered carbon (I D )on the Raman spectra [110,121].High electronic con-ductivity and better performance are achieved by using organic precursors having carbon-ring structures,such as polystyrene and sugar [44,111,121,119,130].With high-quality carbon coatings,the amount of conductive carbons used in cathode preparation can be reduced [49,131].The ideal carbon coating needs to be dense,uniform,graphite-like,2–3nm thick and 1–3wt.%[49,123].

Coating the LiFePO 4particles with other conductive ?lms,such as polypyrrole or Fe 2P,also improves their electrochemical perfor-mance [74,111,117,132].4.4.Conductive carbon

Conductive carbon powders are added in the cathode to improve the electronic contact between the active powders and the elec-

2968W.-J.Zhang/Journal of Power Sources196 (2011) 2962–2970

tronic conductor.The loading of conductive carbon and the mixing procedure signi?cantly affect the electrochemical performance of the prepared cells[39,42–45].Higher conductive carbon loading generally improves the rate capacity but reduces the energy den-sity of the cells.In addition,a uniform distribution of the conductive carbon particles in the cathode through extensive or wet mixing is also important[39,42,43,49].The in?uence of particle size,loading and mixing procedure of conductive carbons on the performance of battery cells needs further attentions.

4.5.Synthesis methods

The LiFePO4powders have been prepared by a variety of syn-thesis techniques,including ball milling[133–137],solid-state reaction[40,138],microwave[139–141],carbothermal reduc-tion[142–145],hydrothermal reaction[146–150],co-precipitation [14,151],sol–gel[152–155],spray-pyrolysis[41,156,157],and rhe-ological method[158–160].For large-scale industrial applications, low processing cost and easy manufacturing are the primary requirements for any synthesis methods.Therefore,the current discussion concentrates on two processes that have been used for commercial production:mechanochemical activation(MA)and carbothermal reduction(CR),although excellent performance has been achieved in materials prepared by other methods[7].

In the MA process,the precursors,such as Li2CO3,FeC2O4, NH4H2PO4and sucrose,are thoroughly crushed and mixed in a high energy ball mill;as a result,the sintering temperature and time necessary to obtain a fully crystallized material is reduced and small particle size is maintained[22,119,136].The milling time is normally4–24h,and the optimum sintering conditions are reported to be600–700?C for4–24h,varied in different studies [119,135,137,161].At high sintering temperatures,the formation of impurity phases,such as Fe2P and Fe3P,were observed.The presence of Fe2P impurities decreases the capacity density and the cyclic stability of LiFePO4.The disadvantages of this process are its long processing cycle and high energy consumption,which inevitably increase the manufacturing cost.In addition,the particle size distribution of MA powders is relatively broad.To reduce the processing cost,additional studies are needed to understand the structure and surface change during sintering and to shorten the processing cycle while maintaining good electrochemical proper-ties.The sintering time can be reduced by increasing the sintering temperature when the carbon coating is present[162].Sintering at high temperatures improves the electronic conductivity of carbon coating,while a short sintering time and fast cooling inhibit particle growth.For massive industrial production,a continuous manufac-turing process is highly desired,especially when advanced heating techniques such as infrared or laser heating are employed.

In the CR process,a low-cost Fe3+-precursor such as Fe2O3or FePO4is used as Fe source instead of the expensive Fe2+precursors, e.g.,FeC2O4and Fe(OOCH3)2[142,145,158,160].The Fe3+is reduced by the fresh formed carbon from the pyrolysis of precursors during sintering.Thus,the cost of CR-LiFePO4/carbon is expected to be low while their tap density is relatively high.Similar to the MA method,the CR process needs to be further optimized to reduce the processing time and energy consumption while maintaining the performance by controlling the particle size and impurity content.

5.Future research needs

It is of scienti?c and engineering importance to understand the Li insertion/extraction mechanism under real operation conditions and at low temperatures.Further investigation on the phase trans-formation in nanosized LiFePO4particles(<40nm)is also merited. To clarify the effect of doping on the electronic and ionic conduc-tivity of LiFePO4,well-designed experiments are needed to exclude the contribution of other factors,such as surface coating or parti-cle size.For engineering applications,more efforts are warranted to prepare LiFePO4materials with a combination of good perfor-mance,high tap density and low processing cost.Modeling and experimental works on the electrode structure design are required to increase the energy density of battery cells.In addition,the abuse tolerance,low-temperature performance and the long-term stabil-ity of LiFePO4under the combined EV/HEV cycles warrant further study.

6.Conclusions

The phase transformation and electrochemical performance of various LiFePO4materials are discussed in light of the technical requirements for EV batteries.The Li insertion/extraction processes in LiFePO4appear to take place through the cooperative motion of electrons and Li-ions along the phase boundaries.As a result, the rate capability of LiFePO4is mainly affected by the transport of electrons from the particle surface to the current collector.Carbon coating and conductive carbon loading are more critical than dop-ing and particle size control when the particles are smaller than 400nm.

The cyclic life of LiFePO4has been signi?cantly improved to over 2000cycles.The migration of iron from the cathode onto the sur-face of graphite anode through electrolyte has been reported to be mainly responsible for the capacity degradation because the deposited iron catalyzes the SEI formation on the anode.Thus,the cycling life of LiFePO4cathode under the combined calendar/cyclic cycles needs to be carefully evaluated for EV applications.The low-temperature performance of LiFePO4can probably be improved by developing novel electrolyte formulations.To meet the stringent technical requirements for EVs,more effort is required to increase the energy density and reduce the energy cost of LiFePO4batteries. Acknowledgements

The author would like to thank Prof.Gary Tepper and Dr.Rus-sell Jamison for a visiting professorship at Virginia Commonwealth University.

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超声雾化提取植物中化学成分.

超声雾化提取植物中化学成分本论文研究了一种新型的提取方法——超声雾化提取法在提取植物化学成分中的应用,并将该提取方法与吹扫技术和液相微萃取相结合建立了多种快速有效的分析方法。利用超声雾化提取法提取大黄中的大黄素、芦荟大黄素和大黄酸。并利用胶束电动毛细管电泳法测定五种市售大黄样品中这些化合物的含量。采用超声雾化提取法提取八角茴香和小茴香中的反式茴香醚,以及花椒中的柠檬烯,优化了实验条件。在优化条件下测得9种样品中被测物的含量。经方法比较后,证实了超声雾化提取适合于提取香料中挥发性成分。将超声雾化提取与吹扫技术相结合,建立了一种在线提取-气相色谱检测方法。并用该方法测定了八角茴香和小茴香中反式茴香醚的含量。这是一种新颖的在线气相取样技术,可用于挥发性化合物的在线提取和测定。将超声雾化提取与顶空液相微萃取结合,利用超声雾化将香料中挥发性成分转移至气相,再通过顶空液相微萃取富集气相被测物后引入气相色谱质谱分析。最终在优化的条件下研究了孜然和花椒中挥发性化合物的组成。与水蒸馏方法相比,该方法具有提取时间短、能耗低等优势。同主题文章 [1]. 王志刚，丁大成，任金莲，刘纯荣，吴胜举，兰涛刘学辉，赵永骞，王长京. 超声雾化法制取金属粉末方法的研究' [J]. 声学技术. 1994.(04) [2]. 王红斗,韦业成,郭煜,李霞冰. 文冠果种仁及其油的化学成分' [J]. Journal of Integrative Plant Biology. 1981.(04) [3]. 向仁德,徐任生. 南五加皮化学成分的研究' [J]. Journal of Integrative Plant Biology. 1983.(04) [4]. 谭宁华,赵守训,陈昌祥,周俊. 太子参的化学成分' [J]. 云南植物研究. 1991.(04) [5]. 王葳,张秀珍. 我国枣树资源及其化学成分' [J]. 中国野生植物资源. 1991.(04) [6]. 刘伯衡,李学禹,田丽萍,魏琳. 新疆产甘草属植物化学成分的研究' [J]. 干旱区研究. 1992.(01) [7]. 黎彤,李峰. 西藏地壳模型及其化学成分初探' [J]. 中国科学技术大学学报. 1992.(04)

不锈钢检测液

如何识别不锈钢【提醒：用磁铁鉴别不了伪劣不锈钢】人们往往认为，“不锈钢”就是“不生锈的钢”，如果生锈了，那肯定就是假冒伪劣产品了。这种认识当然是过于简单了。首先不锈钢的“不锈”，并不是绝对地不生锈，而是相对地在一定条件下的不生锈。如果用户使用不当，将其用在超出其耐蚀能力的环境或条件下，自然也会生锈。二是产品所用不锈钢材料出现腐蚀生锈的情况，也可能是因为厂家选材不合理，即厂家针对其产品用途而选用了不合适的不锈钢牌号做原材料，也可能是厂家的生产加工技术不过关。此外，那就是厂家确实选用了市场上不符合有关国家或行业权威标准的伪劣不锈钢做原材料。不管怎样，这些都是厂家在采购和加工时应该面对和解决的。针对当前市场上确实还存在的生产、销售劣质不锈钢的情况，以及以次充好，伪造质量证明书等市场欺骗行为，我们在采购不锈钢材料时怎样才能掌握主动，快速地识破这些欺骗行为，免遭伪劣不锈钢的危害呢？对于这些可能同样亮丽的不锈钢，要从外观上区分其真假优劣，即使作为专家也恐难做到，那究竟还有没有什么简便易行的办法呢？有人说：这很简单，用磁铁吸！吸不住的就是好的，是“不锈钢”，吸住的就是差的，是“不锈铁”！目前这种说法、做法似乎很流行，甚至有科技刊物、电视节目都推行过此法。对于这种说法、做法，行业专家给予了否定，是不科学和极其错误的。目前世界上已开发应用的五大类不锈钢中，只有奥氏体不锈钢（众多300系列牌号、200系列牌号）往往无磁性（加工后或有弱磁性），而铁素体不锈钢（众多400系列牌号）、双相不锈钢、马氏体不锈钢、沉淀硬化不锈钢都带有磁性。无论有无磁性，每种不锈钢都有其特点和适用的范围。300系奥氏体不锈钢应用最为广泛，而带磁性的现代铁素体等类型的不锈钢的使用比例也越来越高，在餐厨具制品、家电器具、装饰、汽车排气系统、石化等民用、工业领域可以部分替代300系奥氏体不锈钢。对于200系这种磁铁“吸不住”的奥氏体不锈钢，以锰、氮代镍，比相应的300系钢降低了成本，提高了强度，但因为其耐腐蚀性下降，使得其应用领域较窄，往往是那些要求强度高、无磁性且耐蚀性要求不高的领域，如弹簧、电子设备等。而对于目前盛行于中国市场上的所谓的“200系不锈钢”，其耐腐蚀性和使用价值更是低下。这些产品没有按照已有的国家标准生产，而是按照其很不严格的企业标准降低了钢中的镍、铬含量，增加了锰含量，其中有的甚至镍降到了1％以下,铬降到了10％以下，锰增到了14％以上，其点蚀当量极低，远远达不到相应的国家标准规定。从耐腐蚀性讲，这些产品甚至不能称为不锈钢，也根本不能称之为200系不锈钢。在目前的中国不锈钢市场，可以说几乎没有真正的200系不锈钢，市场上所谓的“200系不锈钢”就是目前最大的问题钢、伪劣钢，但它却又和300系奥氏体不锈钢一样，恰恰是无磁的奥氏体钢！可以说，在当前的中国市场采用磁铁吸来鉴别不锈钢的优劣，往往会纵容伪劣不锈钢，而排挤了优质的有磁性的铁素体等钢种，同时也因成本因素排挤了无磁的300系奥氏体不锈钢，甚至可能使这种伪劣钢被假冒成无磁的300系奥氏体不锈钢而用在工业上。通过用磁铁吸来鉴别不锈钢真假优劣显然是不行的，那有没有其它切实可行的简便方法呢？答案是肯定的。在此就介绍一种简便的方法，即使用不锈钢测定液鉴别，就是通过观察测定液在溶解所测钢的过程中产生的颜色变化特点来测定或区分所测钢的一些情况。“颜色变化”往往与所测钢中的镍（Ni）、钼（Mo）、锰（Mn）等特定元素有关。目前我国市场上的不锈钢测定液产品有很多，有从日本等国进口的，也有很多是国产的。特别是在我国不锈钢产业及不锈废钢回收业比较发达的地区，如江苏戴南、无锡，广东佛山，浙江宁波等地，出现了一些专门研制不锈钢测定液的厂家，而先前一些从事化工技术、化学试剂的企业，也针对不锈钢行业的需要先后研制出了不锈钢测定液。目前我国不锈钢测定液虽然品牌众多，但产品似乎雷同，基本上可分为不需用电池和需配用电池的两类。不需用电池的这种往往没有再细分，主要是通过观看测定液滴在不锈钢表面后颜色的变化，再比照色谱进行区分。如市场上有种被称为“304型”的，它标有四个标准颜色对应四种不锈钢牌号———201、202、301、304，其中201对应深红色，202对应红色，301对应浅红色，304对应无色或淡黄色。这些颜色是指用该测定液对相应钢种做试验时分别呈现出的颜色。用电池的测定液有很多种，如“Mo2、低Ni、Ni2、Ni4、Ni6、Ni8、Ni14、Ni20、Ni40、Ni60”等，有的产品在标识上用“N”代替“Ni”。这些产品单独使用或配合使用可以测定钢中镍（Ni）、钼（Mo）、锰（Mn）等相应元素的大致含量（百分比），然后可比照国家有关权威标准含量来区分钢的真假优劣。比如“Ni8”测定液,使用时先将适量的“Ni8”药水滴在干净的钢表面上，然后将有充足电量的专用电池（一般是9V，厂商可以配售）的正极接钢板，负极接上钢表面上的“Ni8”药珠（注意不要接触到钢表面），几秒钟后停止通电以观察钢表面上药珠的颜色变化，若颜色变红，则表明钢中含镍在8％左右及以上，否则药珠颜色会变淡黄或不变。再如“低Ni”液定液，是种测定低镍（Ni）高锰（Mn）不锈

304不锈钢化学成分

304不锈钢化学成分https://www.sodocs.net/doc/544601632.html,work Information Technology Company.2020YEAR

304不锈钢化学成分 304不锈钢化学成分规格C Si Mn P S Cr Ni Mo SUS431≤0.08 ≤1.00 ≤2.00 ≤0.05 ≤0.03 18.00-20.00 8025~10.50- 304不锈钢管就是0Cr18Ni9。 304不锈钢管；屈服强度≥205 抗拉强度≥520 延伸率≥40 硬度HB≤187 HRB≤90 HV≤200 熔点 1398~1420℃ 1.使用环境中存在氯离子。氯离子广泛存在，比如食盐、汗迹、海水、海风、土壤等等。不锈钢在氯离子存在下的环境中，腐蚀很快，甚至超过普通的低碳钢、所以对不锈钢的使用环境有要求，而且需要经常擦拭，出去灰尘，保持清洁干燥。 2.没有经过固溶处理。合金元素没有溶入基体，致使基本组织合金含量低，抗蚀性能差。

3.这种不含钛和铌的材料有天生的晶间腐蚀的倾向。加入钛和铌，再配以稳定处理，可以减少晶间腐蚀。在空气中或化学腐蚀介质中能够抵抗腐蚀的一种高合金钢，不锈钢是具有美观的表面和耐腐蚀性能好，不必经过镀色等表面处理，而发挥不锈钢所固有的表面性能，使用于多方面的钢铁的一种，通常称为不锈钢。代表性能的有13铬钢，18-8铬镍钢等高合金钢。从金相学角度分析，因为不锈钢含有铬而使表面形成很薄的铬膜，这个膜隔离开与钢内侵入的氧气起耐腐蚀的作用。为了保持不锈钢所固有的耐腐蚀性，刚必须含有12%以上的铬。 304是一种拥有性的不锈钢，它广泛地用于制作要求良好综合性能（耐腐蚀和成形性）的设备和机件。 304不锈钢是按照美国ASTM标准生产出来的不锈钢的一个牌号。304相当于我国的OCr19Ni9(OCr18Ni9)不锈钢。304含19铬%，含镍9%。 304不锈钢化学成分 304是得到最广泛应用的不锈钢、耐热钢。用于食品生产设备、昔通化工设备、核能等.

304不锈钢板化学成分

304不锈钢板化学成分 304不锈钢板 304不锈钢板材不锈钢卷板不锈钢冲孔板不锈钢防护板不锈钢花纹板不锈钢薄板不锈钢镜面板拉丝板 ......... 牌号： 0Cr18Ni9（0Cr19Ni9）化学成分为： C：≤0.08 ， Si ：≤1.0 ， Mn ：≤2.0 ， Cr ：18.0～20.0 ， Ni ：8.0～10.5， S ：≤0.03 ， P ：≤0.035。 304不锈钢板基本概述按制法分热轧和冷轧的两种，按钢种的组织特征分为5类：奥氏体型、奥氏体-铁素体型、铁素体型、马氏体型、沉淀硬化型。要求能承受草酸、硫酸-硫酸铁、硝酸、硝酸-氢氟酸、硫酸-硫酸铜、磷酸、甲酸、乙酸等各种酸的腐蚀，广泛用于化工、食品、医药、造纸、石油、原子能等工业，以及建筑、厨具、餐具、车辆、家用电器各类零部件。不锈钢板表面光洁，有较高的塑性、韧性和机械强度，耐酸、碱性气体、溶液和其他介质的腐蚀。它是一种不容易生锈的合金钢，但不是绝对不生锈。聊城三得利不锈钢的耐腐蚀性主要取决于它的合金成分（铬、镍、钛、硅、铝等）和内部的组织结构，起主要作用的是铬元素。铬具有很高的化学稳定性，能在钢表面形成钝化膜，使金属与外界隔离开来，保护钢板不被氧化，增加钢板的抗腐蚀能力。钝化膜破坏后，抗腐蚀性就下降。国标304不锈钢的性质抗拉强度(Mpa) 520 屈服强度(Mpa) 205-210 伸长率(%) 40% 硬度 HB187 HRB90 HV200 304不锈钢的密度7.93 g/cm3奥氏体不锈钢一般都用这个值304含铬量(%) 17.00-19.00，含镍量.（%）8.00-10.00，304相当于我国的0Cr19Ni9 (0Cr18Ni9)不锈钢 304不锈钢是一种通用性的不锈钢材料，防锈性能比200系列的不锈钢材料要强。耐高温方面也比较好。304不锈钢具有优良的不锈耐腐蚀性能和较好的抗晶间腐蚀性能。对氧化性酸，在实验中得出：浓度

不锈钢检测方法

不锈钢检测方法目前使用不锈钢测定液来鉴别不锈钢，其实只是在一定程度上回答了“不是什么”的问题，而不能真正地回答“确切是什么”的问题。例如：用“304型”测定液或“Ni8”型测定液测试商家所谓的“304”产品，如果测试结果与真304产品的相同，我们万万不可就此断定它就是304，而只能说“可能”是304。因为不管是通电型还是不用通电型的，测试的结果只是我们判断所测钢是某钢种（如304）的一个必要而非充分的条件。如果我们想真正弄清楚钢的确切牌号，那么就必须通过专业的化学分析或光谱分析等方法，全面测定它的化学成分，再对照有关权威标准进行鉴别。当然这些方法与使用不锈钢测定液相比，更加专业和准确，但在难度或成本方面也高了不少。另外，不锈钢材料的质量高低不仅仅是由其化学成分决定的，还与其组织、性能、纯净度等因素有关。而对于这些因素的测定，不锈钢测定液显然是无能为力的，只有借助于有关专业的测试检验。目前市场上的不锈钢测定液产品，在标识等方面还存在不够科学的地方。如上面提及的用“N”代替“Ni”的情况，还有的将200系不锈钢分为“200、201、202”等。在实际使用过程中也发现，有的测试结果用肉眼观察难以区分，容易导致错误。如测试时除了201、202和301、304之间有比较明显的颜色区别外，201和202之间、301和304之间的颜色变化就不是很明显。这些不科学及不足的地方还需有关厂商进一步改进。不管怎样，在采购不锈钢产品时，除了要注意产品的出厂检验合格证书或质量证明书，要注重商家的信誉，而不要贪图便宜外，我们在识破市场欺骗行为和伪劣不锈钢产品真面目方面，还是可以主动采取一些行动的。目前市场上小瓶装的不锈钢测定液，体积都较小，重量也轻，携带方便，费用成本低（每瓶的价格分品种从十几元到二三十元不等，每次测试的费用有的只有几分钱），测试操作也很简单，不失为一种有力的工具和“武器”，我们不妨一试！使用不锈钢测定液，我们在一定程度上就能很轻易地识破市场上的一些欺骗行为和伪劣不锈钢的真面目。比如要买304牌号的不锈钢，我们就可对厂商提供的“304”产品进行测试。如是真的304，我们用上述“304型”测定液或“Ni8”型测定液测试，就应该出现相应的测试结果，否则，就不是真的304；如果再用“低Ni”测定液进一步测试发现药珠呈紫红色，则表明该产品是种含锰较高的钢，也很可能是当前市场上盛行的耐腐蚀性很低的伪劣不锈钢，即所谓的“200系不锈钢”。在使用测量不锈钢中特定元素大致含量的测定液进行有关测试鉴别时，要求我们参照和了解有关不锈钢国家标准中对化学成份的规定。

不锈钢化学成分

不锈钢化学成分文档编制序号：[KK8UY-LL9IO69-TTO6M3-MTOL89-FTT688]

? 产品名称标准：不锈钢GB1220-92 牌号：化学成分% C：≤0.07 Si ：≤1.0 Mn ：≤2.0 Cr ：17.0～19.0 Ni ：8.0～11.0 Mo ： Cu ： Ti ： S ：≤0.03 P ：≤0.035 Al ：美国：304

日本：SUS304 德国：X5Cr-Ni18.9 各种不锈钢的耐腐蚀性能 304 是一种通用性的不锈钢，它广泛地用于制作要求良好综合性能（耐腐蚀和成型性）的设备和机件。 301 不锈钢在形变时呈现出明显的加工硬化现象，被用于要求较高强度的各种场合。 302 不锈钢实质上就是含碳量更高的304不锈钢的变种，通过冷轧可使其获得较高的强度。 302B 是一种含硅量较高的不锈钢，它具有较高的抗高温氧化性能。 303和303Se 是分别含有硫和硒的易切削不锈钢，用于主要要求易切削和表而光浩度高的场合。303Se不锈钢也用于制作需要热镦的机件，因为在这类条件下，这种不锈钢具有良好的可热加工性。

304L 是碳含量较低的304不锈钢的变种，用于需要焊接的场合。较低的碳含量使得在靠近焊缝的热影响区中所析出的碳化物减至最少，而碳化物的析出可能导致不锈钢在某些环境中产生晶间腐蚀（焊接侵蚀）。 304N 是一种含氮的不锈钢，加氮是为了提高钢的强度。 305和384 不锈钢含有较高的镍，其加工硬化率低，适用于对冷成型性要求高的各种场合。 308 不锈钢用于制作焊条。 309、310、314及330 不锈钢的镍、铬含量都比较高，为的是提高钢在高温下的抗氧化性能和蠕变强度。而30S5和310S乃是309和310不锈钢的变种，所不同者只是碳含量较低，为的是使焊缝附近所析出的碳化物减至最少。330不锈钢有着特别高的抗渗碳能力和抗热震性． 316和317 型不锈钢含有铝，因而在海洋和化学工业环境中的抗点腐蚀能力大大地优于304不锈钢。其中，316型不锈钢由变种包括低碳不锈钢316L、含氮的高强度不锈钢316N以及合硫量较高的易切削不锈钢316F。

植物化学成分数据库用户操作手册

3.2.22 植物化学成分数据库数据库介绍：本数据库目前收录了上海有机所采集的植物化学成分数据，信息包括了植物分类信息、植物图片、分离出的化学成分、相关研究文献等。共收集化学物质8万种，用户可通过输入植物物种名称、植物科属描述信息、化合物检索数据库，并可用名录浏览部分蔬菜与水果的化学成分并进行成分比较，可了解植物的共有成分。图3.2.22.1 植物成分数据库首页图3.2.22.2 从植物名称检索植物本数据库所有的检索结果，都以植物列表显示。用户可点击植物名对应的超链接查看植物信息。检索方式与示例：

可输入中文、拉丁文、英文名，例如“Amaranthaceae”，或者“Amaranth family”，或者“百合”，“相思子”，“丝瓜”等。对每一种名称均进行模糊检索。如图3.2.22.2，输入“丝瓜”模糊检索中文名包括了“丝瓜”的植物（例1），检索结果如图3.2.22.3，有丝瓜和广东丝瓜两个结果。图3.2.22.3 从植物名称检索植物的结果植物检索结果列表中包括植物名和链接、植物分级、缩微图片、化学成分的链接，并可将植物加入收藏夹。鼠标放在缩微图片上，便可在窗口里自动放大图片局部。图3.2.22.4 查看植物详细信息

物的成分。化学成分的信息，包括了有机所化合物登录号(点击号码链接可查看化合物详细信息)、结构、名称和分子式。注意：本数据库收集的植物成分，并非植物的全部成分，只是文献研究提到的成分。图3.2.22.5 植物的部分化学成分图3.2.22.6 查看化合物的详细信息图3.2.22.3中点击“广东丝瓜”的链接，便可查看广东丝瓜的信息，如图3.2.22.7. 广东丝瓜的化学成分如图3.2.22.8.

不锈钢检测方法

不锈钢检测方法内部编号：（YUUT-TBBY-MMUT-URRUY-UOOY-DBUYI-0128）

中药化学——植物化学成分的生源学说

植物中众多的化学成分有许多已阐明了它们的化学结构和药理作用，其中不少已用于临床。这些成分中有的已可用化学的或生物的方法进行合成。但尚存在的问题是：这些成分在植物体内是怎样形成的？是由何种物质、经过什么新陈代谢途径形成的？为了解决这个问题，许多植物学、生物学、植物化学、生化学的研究工作者从可能的新陈代谢过程，生物化学反应等多方面地进行推测这些成分在植物体内的形成过程，这就是植物化学成分的生源学说（Biogenesis Biogenetic Origin）。植物化学成分的生源研究主要是研究各类成分在体内生物合成的途径，各种酶在过程中所起的作用以及过程中所产生的各种中间产物的化学并测定它们的结构。生源的研究有多种设想与途径，因而也形成了多种学说，如异戊二烯法则、醋酸学说等已普遍应用于研究药用植物有效成分的生物合成及其途径。随着同位素示踪技术和化学技术的发展，生源研究的进展也更为迅速。生源研究的意义基本上可归纳为下列几点： 1. 了解了各类成分的生物合成途径以及某种成分最初由何种物质（这种物质称为前体Precursors）形成和各种中间产物后，就可以人为地于植物中注入前体或中间产物来增加所需成分的积累和产量。达到人工控制、定向培育的目的。例如于枸椽酸的新陈代谢途径中加入乌头酶（Aconilase）就可以增加枸椽酸在植物体内的积累，因枸椽酸的生成过程中必须有此种酶的存在。这是研究植物生源最主要的目的。但是，前体并非一成不变，例如熊果甙在不同科时它们的生源就有可能不同。 2.从生源关系密切的成分中来扩大生物活性物质的资源。如三萜类与许多甾体衍生物类在生源上具密切关系，甾体衍生物类常具多种生物活性，三萜类成分在植物界分布广泛，故有可能从三萜类成分来寻找具广泛生物活性的物质。 3.从生源学说来确定某类成分的结构类别。如四环三萜类成分原分类不属于三萜，以后通过生源关系的探讨，才明确地将它们划在三萜范围内。 4.了解某类成分在植物体内的原始状态与代谢途径后，就可以为进行植物成分的生物合成提供理论规律，这将能更好地对生产与实践（如生药的采收时间与部位，有效成分的合成等）起指导作用。植物体内各种成分的生源基本上可分为两类，一类是植物本身必须的营养物质如糖类，脂肪、蛋白质等成分的新陈代谢途径，一类是植物次生物质，如生物碱、甙类、萜类等成分的新陈代谢途径。有关这些代谢途径的学说很多，其中不少还是设想，例如认为醋酸酯一丙二酸酯（Acetate-Melonate）途径合成脂肪酸、酚性化合物、蒽醌等成分，3，5-羟基一3-甲基戊酸酯（Mevalonate）途径合成萜类、甾类等成分，莽草酸（shikimicacid）途径合成芳香族氨基酸、有机酸及其他化合物；氨基酸途径合成生物碱等成分。 1.植物体内各类成分的生源关系 2.各类植物次生物的生源学说，列举数例说明它们的生物合成途径（1）有机酸类：有14C可以说明许多较复杂的有机酸类由 CH3COOH形成，如上所述6-甲基不杨酸的生物合成途径；（2）生物碱：生物碱的生源学说曾有多种路线的设想，但目前己主要集中一种学说，即生物碱是由醋酸、单萜和多种简单氨基酸如苯丙氨酸（Phenylalanine）、色氨酸（TrYptophan）、蛋氨酸（Meih1onine），鸟氨酸（Ornithine）等作为前体而形成的。这些理论因为标记化合物的发展已可用实验证实。方法是给予植株以一定的具标记元素的化合物为前体，（常用的为具14C的化合物），待植株经过一定时期的生长后，分离生物碱，从前体与生成物标记元素的位置来确定二者之间的关系。由于应用了这种技术，许多生物碱如烟碱（Nicoitine）、）吗啡（Morphine）、莨菪碱（Hyoscyamine）、秋水仙碱（Col一chicine）、罂粟碱（Papaverine）、芦竹碱（Gramine）等已证明是由氨基酸形成。有些简单的生物碱已可按生源学说途径在实验室里用氨基酸进行人工合成。目前关于生物碱的生源研究有一较大的突破，即认为除了上述各种前体外，还有许多特殊的中间物质参与了生物合成过程。（3）香豆精类（4）蒽醌类：许多蒽醌类成分在植物体内的前体至今未完全确定。有的学者认为苔藓酸（Orsellinic acid，广泛分布于地衣和真菌）为一前体。由其形成蒽醌类成分的生源学说路线。（5）萜类：一般认为由CH3COOH与辅酶A（CoenzymeA，简作：CO.A）缩合成酯，再经过脱水、氧化-还原、环化、分子重排等反应形成C5——C10——C15——C20

不锈钢化学成分检测

不锈钢化学成分检测不锈钢材料具有良好的耐蚀性、优异的成型性、较高的强度等良好的综合材料性能。那它究竟有什么化学成分呢?以下是本人要与大家分享的：不锈钢化学成分检测，供大家参考! 不锈钢化学成分检测一在进行化学成分检验时，常用的药水有N低、 Ni4(201)、Ni6(301)、Ni8(304)、Ni20(310)等，具体方法如下： 1.名称：不锈钢水箱使用的不锈钢化学成份检测药水,低镍系列(N低) 说明：测定金属的化学成份中是否含镍使用方法例：将该分析测定夜滴一滴于钢表面，用 9V电池，正极搭钢，负极搭测定液珠上面，通电氧化，氧化后呈紫红色，则证明该不锈钢水箱使用的不锈钢中含镍量在5.5%以下，锰含量一般≥6%，反之不显红色的，一般是301或304材质。 2.名称：不锈钢水箱使用的不锈钢化学成份检测药水,201系列(Ni4) 说明：测定不锈钢水箱使用的不锈钢的化学成份中含镍量是否达到3.5%以上。使用方法例：将该分析测定夜滴一滴于钢表面，用 9V电池，正极搭钢，负极搭测定液珠上面，通电氧化，氧化后呈粉红色络合物，则证明该不锈钢水箱使用的不锈钢中镍的含量≥4%，即已达到201系列标准。 3.名称：不锈钢水箱使用的不锈钢化学成份检测药水,301系列(Ni6)

说明：测定不锈钢水箱使用的不锈钢的化学成份中含镍量是否达到5.5%以上。使用方法例：将该分析测定夜滴一滴于钢表面，用 9V电池，正极搭钢，负极搭测定液珠上面，通电氧化，氧化后呈粉红色络合物，则证明该不锈钢水箱使用的不锈钢中镍的含量≥6%，即已达到301系列标准。 4.名称：不锈钢水箱使用的不锈钢化学成份检测药水,304系列(Ni8) 说明：测定不锈钢水箱使用的不锈钢的化学成份中含镍是否达到7.8%以上。使用方法例：将该分析测定夜滴一滴于钢表面，用 9V电池，正极搭钢，负极搭测定液珠上面，通电氧化后呈红色，则证明它的含镍量≥8%，若不呈红色则证明该不锈钢水箱使用的不锈钢中含镍量小于8%，即未达到304材质标准。 5.名称：不锈钢水箱使用的不锈钢化学成份检测药水,310高温材质系列(Ni20) 说明：测定不锈钢水箱使用的不锈钢的化学成份中含镍是否达到18%以上使用方法例：将该分析测定夜滴一滴于钢表面，用 9V电池，正极搭钢，负极搭测定液珠上面，通电氧化，氧化后呈黄色,则表明该不锈钢水箱使用的不锈钢含镍为0-14%;氧化后呈老黄色,则表明该不锈钢水箱使用的不锈钢含镍在14%左右;氧化后呈红色络合物,则表明该不锈钢水箱使用的不锈钢含镍在20%左右，，即达到310标准;氧化后呈粉红色络合物,则表明该不锈钢水箱使用的不锈钢含镍在35%左右;氧化后呈红色钢表面淡黑斑,则表明该不锈钢水箱使用的不锈钢含镍在60%左右;氧化后呈红色钢表面重黑斑,则表明该不锈钢水箱使

不锈钢化学成分测定液产品使用说明

不锈钢化学成份测定液产品使用说明使用要求： 1、不锈钢表面须处理干净（油污，灰尘，表面氧化皮等）可用锉刀或磨光机处理平整。否则，将造成较大误差，测定结果不准确。 2、电池应保持足够电量（足够的电量是保证电解反应充分进行的前提），若发现电量不足，应及时更换。 3、电池正极（＋）搭接金属表面，负极（－）搭接测定液，瞬间通电氧化。操作时切忌将负极触碰到不锈钢，且通电时间须控制好(出现颜色立即停止)，否则易产生误差。 4、测定液不能过多也不能过少，须滴成一滴小小的水珠状。一、Ni定性测定液：该产品是假不锈钢的克星，并能快速确定不锈钢产品中镍含量的大致范围。操作方法：滴一小滴测定液于待测金属表面，瞬间通电氧化后，液滴将发生颜色变化，静置片刻（约．．．．．．1．分钟）至液滴颜色稳定．．．．．．．．．．，观察其现象。 1、若无玫瑰红出现直接生成浅黄色或淡白色，表明该材料不含Ni成份； 2、若生成玫瑰红后褪为浅黄色，表明该材料含Ni<2.5%左右； 3、若生成玫瑰红且不褪色，表明该材料含Ni≥2.5%左右；静止片刻后观察其颜色深浅程度，若液滴呈淡玫瑰红且略泛黄表明 2.5%≤Ni≤5.5%；若无泛黄，Ni＞5.5％；玫瑰红越深越鲜艳表明含N i量越高。二、低N i测定液：该N i低分析测定液用于专业测定真假不锈钢。主要用于测定200、201、202系列低Ni高Mn钢。操作方法：滴一小滴测定液于待测金属表面，瞬间通电氧化，生成玫瑰红且不褪色，表明该材料含Ni <2%，Mn≥6%。三、Ni 2测定液：滴一小滴测定液于待测金属表面，瞬间通电氧化， 1、若无玫瑰红出现直接生成淡黄色或淡白色，表明该材料含Ni<2%； 2、若生成玫瑰红络合物且不褪色，表明该材料含Ni≥2%。注意通电氧化有颜色即停止，一般颜色较淡。四、Ni 4测定液：该产品主要用于测定201、202材料。操作方法：滴一小滴测定液于待测金属表面，瞬间通电氧化， 1、若无玫瑰红出现直接生成淡黄色或淡白色，表明该材料含Ni<3.5%； 2、若生成玫瑰红络合物且不褪色，表明该材料含Ni≥3.5%。注意通电氧化有颜色即停止，一般颜色较淡。五、Ni 6测定液：该产品主要用于测定301材料；操作方法：滴一小滴测定液于待测金属表面，瞬间通电氧化， 1、若生成玫瑰红络合物且不褪色，表明该材料含Ni≥5.5％；注意通电氧化有颜色即停止，一般颜色较淡。 2、若无玫瑰红出现直接生成淡黄色或淡白色，表明该材料含Ni <5.5％。六、Ni 8测定液：该产品主要用于测定304材料；操作方法：滴一小滴测定液于待测金属表面，通电氧化，该产品通电氧化时略长于其它产品，当氧化有颜色出现停止。 1、若生成红色络合物且不褪色，表明该材料含Ni≥7.5％；一般颜色较淡。 2、若无红色出现直接生成淡黄色或淡白色，表明该材料含Ni <7.5％。七、Mo 2测定液：该产品常用于316材料，2080高温合金材料；操作方法：滴一小滴测定液于待测金属表面，瞬间通电氧化， 1、若生成玫瑰红络合物且不褪色，表明该材料含Mo≥2％； 2、若生成红色络合物立即褪色，表明该材料不含Mo； 3、若生成玫瑰红络合物且马上褪为深黄色，表明该材料含Mo<2％。 4、若无红色出现，迅速生成绿色络合物，表明该材料是2080高温合金材料。说明：Ni5Mo3，Ni7Mo2这两种材料红色络合物也不褪色，但这两种材料不是316材料，真正316材料是无磁性的，而这两种材料有很大磁性，另外（904L）00Cr23Ni23Mo4Cu也不褪色。八、Ni14测定液：该产品主要用于测定309材料；操作方法：滴一小滴测定液于待测金属表面，瞬间通电氧化， 1、若生成玫瑰红络合物且不褪色，表明该材料含Ni≥12％； 2、若无玫瑰红色出现直接生成淡黄色或淡白色，表明该材料含Ni <12％。九、Ni20测定液：该产品主要用于测定310材料；操作方法：滴一小滴测定液于待测金属表面，瞬间通电氧化， 1、若生成黄色，则表明该材料含镍<14%； 2、若生成老黄色，则表明该材料含镍在14%左右； 3、若生成玫瑰红色络合物，则表明该材料含镍在20%左右，即达到310标准； 4、若生成粉红色络合物，则表明该材料含镍在35%左右； 5、若生成玫瑰红色钢表面淡黑斑，则表明该材料含镍在60%左右； 6、若生成玫瑰红色钢表面重黑斑，则表明该材料含镍在70%左右； 7、若生成绿色带点红，则表明该材料为康铜合金十、Ni40测定液：测定不锈钢的含镍量是否达到32%以上操作方法：滴一小滴测定液于待测金属表面，瞬间通电氧化， 1、若生成玫瑰红络合物且不褪色，表明该材料含镍≥32%；

植物化学成分测定

在植物组织或农畜产品分析中，样品经高温灼烧，有机物中的碳、氢、氧等物质与氧结合成二氧化碳和水蒸汽而碳化，残留物呈无色或灰白色的氧化物称为“总灰分”。它主要是各种金属元素的碳酸盐、硫酸盐、磷酸盐、硅酸盐、氯化物等。本章分为植物灰分测定、植物常量元素的测定、植物微量元素分析三节。由于植物的各种营养元素的分析测定方法在土壤分析部分大多已作介绍，学习的重点在灰分的测定，干灰化、湿灰化制备植物分析待测上，掌握分析待测液的制备方法和要点。在植物组织或农畜产品分析中，样品经高温灼烧，有机物中的碳、氢、氧等物质与氧结合成二氧化碳和水蒸汽而碳化，残留物呈无色或灰白色的氧化物称为“总灰分”。它主要是各种金属元素的碳酸盐、硫酸盐、磷酸盐、硅酸盐、氯化物等。动物性原料的灰分含量由饲料的组分、动物品种及其它因素决定，植物性原料的灰分含量及其组分则由自然条件、成熟度等因素决定。此外灼烧条件也会影响分析结果，而且残留物(灰分)与样品中原有的无机物并不完全相同，因此用干灰化法测得的灰分只能是“粗灰分”。总灰分含量是品质分析中经常测定的项目之一，它是产品中无机营养物质的总和。测定植株各部分灰分含量可以了解各种作物在不同生育期和不同器官中灰分及其变动情况，如用于确定饲料作物收获期有重要参考价值。此外，样品在适当条件下灰化后，除了测定“总灰分”，必要时还可以在其中测定各组成分——灰分元素，如：氮、磷、钾、钙、镁、钠和多种微量元素，它们也是评价营养状况的参考指标之一。现在常用的灰分测定方法有下列几种[1]： (1)一般灰化法； (2)灰化后的残灰用水浸湿后再次灰化； (3)灰化后的残灰用热水溶解过滤后再次灰化残渣； (4)添加醋酸镁或硝酸镁或碳酸钙等灰化； (5)添加硫酸灰化。前三种测定方法可以认为本质上相同，即均是“直接灰化法”，目前绝大多数农畜产品均采用此法。对含磷、硫、氯等酸性元素较多，即阴离子相对于阳离子过剩的样品，须在样品中加入一定量的灰化辅助剂，补充足够量的碱性金属元素，如镁盐或钙盐等，使酸性元素形成高熔点的盐类而固定起来，再行灰化。如目前国际上将添加醋酸镁作为肉和肉制品灰分测定的标准方法[5]。而相对于以钾、钙、钠、镁等为主的样品，其阳离子过剩，灰化后的残灰呈碱性碳酸盐的形式，如：大豆、薯类、萝卜、苹果、柑橘等，一般还是采用“直接灰化法”，也可以采用通过添加高沸点的硫酸，使阳离子全部以硫酸盐形式成为一定组分进行定量的方法，目前主要用于糖类制品的灰分测定[2]，此外通过测定食品中的电解质含量，即“电导法”，也可间接测定食品中的总灰分，但目前该法只应用于白砂糖的灰分测定。

不锈钢化学成分

不锈钢化学成分 Revised as of 23 November 2020

? 产品名称标准：不锈钢GB1220-92 牌号：化学成分% C：≤ Si ：≤ Mn ：≤ Cr ：～ Ni ：～ Mo ： Cu ： Ti ： S ：≤ P ：≤Al ：美国：304日本：SUS304德国：各种不锈钢的耐腐蚀性能

304 是一种通用性的不锈钢，它广泛地用于制作要求良好综合性能（耐腐蚀和成型性）的设备和机件。 301 不锈钢在形变时呈现出明显的加工硬化现象，被用于要求较高强度的各种场合。 302 不锈钢实质上就是含碳量更高的304不锈钢的变种，通过冷轧可使其获得较高的强度。 302B 是一种含硅量较高的不锈钢，它具有较高的抗高温氧化性能。 303和303Se 是分别含有硫和硒的易切削不锈钢，用于主要要求易切削和表而光浩度高的场合。303Se不锈钢也用于制作需要热镦的机件，因为在这类条件下，这种不锈钢具有良好的可热加工性。 304L 是碳含量较低的304不锈钢的变种，用于需要焊接的场合。较低的碳含量使得在靠近焊缝的热影响区中所析出的碳化物减至最少，而碳化物的析出可能导致不锈钢在某些环境中产生晶间腐蚀（焊接侵蚀）。 304N 是一种含氮的不锈钢，加氮是为了提高钢的强度。 305和384 不锈钢含有较高的镍，其加工硬化率低，适用于对冷成型性要求高的各种场合。 308 不锈钢用于制作焊条。 309、310、314及330 不锈钢的镍、铬含量都比较高，为的是提高钢在高温下的抗氧化性能和蠕变强度。而30S5和310S乃是309和310不锈钢的变种，所不同者只是碳含量较低，为的是使焊缝附近所析出的碳化物减至最少。330不锈钢有着特别高的抗渗碳能力和抗热震性． 316和317 型不锈钢含有铝，因而在海洋和化学工业环境中的抗点腐蚀能力大大地优于304不锈钢。其中，316型不锈钢由变种包括低碳不锈钢316L、含氮的高强度不锈钢316N以及合硫量较高的易切削不锈钢316F。 321、347及348 是分别以钛，铌加钽、铌稳定化的不锈钢，适宜作高温下使用的焊接构件。348是一种适用于核动力工业的不锈钢，对钽和钻的合量有着一定的限制。

不锈钢检测液如何使用(方便准确)

不锈钢检测液使用方法：名称：不锈钢分析液,低镍系列(N低) 说明：测定金属的化学成份中是否含镍使用方法例：在被测钢无磁性的前提下，将该分析测定夜滴一滴于钢表面，用9V电池，正极搭钢，负极搭测定液珠上面，通电氧化2-5秒，氧化后呈玫瑰红色，则证明该不锈钢中含镍量在5.5%以下，反应后显黄色或无色的，证明镍含量≥6% Ni 2测定液：滴一小滴测定液于待测金属表面，瞬间通电氧化，若无玫瑰红出现直接生成淡黄色或淡白色，表明该材料含Ni<2%；若生成玫瑰红络合物且不褪色，表明该材料含Ni≥2%。注意通电氧化有颜色即停止，一般颜色较淡。名称：不锈钢分析液,201系列(N4) 说明：测定不锈钢的化学成份中含镍量是否达到3.5%以上使用方法例：将该分析测定夜滴一滴于钢表面，用9V电池，正极搭钢，负极搭测定液珠上面，通电氧化5-10秒，氧化后呈粉红色络合物，则证明该不锈钢中镍的含量≥4%，即已达到201系列标准，若显黄色或无色，证明镍小于4% 名称：不锈钢分析液,301系列(N6) 说明：测定不锈钢的化学成份中含镍量是否达到5.5%以上使用方法例：将该分析测定夜滴一滴于钢表面，用9V电池，正极搭钢，负极搭测定液珠上面，通电氧化5-10秒，氧化后呈粉红色络合物，则证明该不锈钢中镍的含量≥5.5%，即已达到301系列标准，呈黄色或无色，证明镍小于5.5%。名称：不锈钢分析液,304系列(N8) 说明：测定不锈钢的化学成份中含镍是否达到8%以上

使用方法例：将该分析测定夜滴一滴于钢表面，用9V电池，正极搭钢，负极搭测定液珠上面，通电氧化5-10秒后呈红色，则证明它的含镍量≥8%，若呈黄色或无色则证明该不锈钢中含镍量小于8%，即未达到304材质标准名称：不锈钢分析液, N10 说明：测定不锈钢的化学成份中含镍是否达到9.6%以上使用方法例：将该分析测定夜滴一滴于钢表面，用9V电池，正极搭钢，负极搭测定液珠上面，通电氧化5-10秒后呈红色，则证明它的含镍量≥9.6%，若呈黄色或无色则证明该不锈钢中含镍量小于9.6% 名称：不锈钢分析液,Ni14系列(N14) 说明：测定不锈钢的化学成份中含镍是否达到11%以上使用方法例：此测药水用鉴别Cr20Ni14、Cr26Ni12、Cr23Ni13(309S)，将该分析测定夜滴一滴于钢表面，用9V电池，正极搭钢，负极搭测定液珠上面，通电氧化5-10秒，呈红色络合物,则表明该不锈钢含镍≥11% 名称：不锈钢分析液,310高温材质系列(N20) 说明：测定不锈钢的化学成份中含镍是否达到18%以上使用方法例：将该分析测定夜滴一滴于钢表面，用9V电池，正极搭钢，负极搭测定液珠上面，通电氧化5-10秒，氧化后呈黄色,则表明该不锈钢含镍为0-14%；氧化后呈老黄色,则表明该不锈钢含镍在14%左右；氧化后呈红色络合物,则表明该不锈钢含镍在20%左右，，即达到310标准；氧化后呈粉红色络合物,则表明该不锈钢含镍在35%左右；氧化后呈红色钢表面淡黑斑,则表明该不锈钢含镍在60%左右；氧化后呈红色钢表面重黑斑,则表明该不锈钢含镍在70%左右；氧化后呈绿色带点红,则表明该合金为康铜名称：不锈钢分析液,高镍系列(N40)

第五章植物化学成分的结构鉴定方法

第五章植物化学成分的结构鉴定 1.结构鉴定的研究程序 2.结构鉴定的一般方法 3.常见天然活性成分的特性及测定方法（自学）第一节结构研究的程序一、化合物纯度的判定方法 1．结晶均匀、一致。 2．熔点明确、敏锐（0.5~1.0℃） 3．TLC (PPC):三种以上不同展开剂展开，均呈现单一斑点。 4．HPLC、GC也可以用于化合物纯度的判断。二、未知化合物的结构分析分子量和分子式的确定推断可能含有的官能团、结构碎片和基本骨架测定分子的平面结构推断并确定分子的构型、构象等的主体结构第二节四大光谱在结构测定中的应用紫外—可见光谱（UV -VIS）——共轭体系特征分子中电子跃迁（从基态至激发态）。 n-π*、π-π* 跃迁可因吸收紫外光及可见光所引起，吸收光谱将出现在光的紫外区和可见区（200～700nm） 200nm 400 700nm 紫外区（UV）可见区（VIS）应用：推断化合物的骨架类型——共轭系统。取代基团的推断。如加入诊断试剂推断黄酮的取代模式（类型、数目、排列方式）用于含量测定（以最大吸收波长作为检测波长进行含量测定）。

红外光谱（IR）分子中价键的伸缩及弯曲振动所引起的吸收而测得的吸收图谱，称为红外光谱。 4000 3600 3000 1500 1000 625cm -1 特征频率区指纹区特征官能团的鉴别化合物真伪的鉴别羟基（酚羟基、醇羟基）3600~3200 cm -1 游离羟基~3600 cm -1 氢键缔合羟基3400~3200 cm -1羰基1600~1800 cm -1酮~1710 cm -1 酯1710~1735cm -1 芳环1600、1580、1500cm -1 有2~3个峰双键1620~1680 cm -1 两个化合物完全相同的条件1、特征区完全吻合2、指纹区也需完全一致 1H-NMR （核磁共振氢谱）: 信息参数：化学位移（δ）、峰面积、峰裂分（s 、d 、t 、q 、m ）及偶合常数（?）（1）化学位移（δppm）: 与1H核所处的化学环境（1H核周围的电子云密度）有关电子云密度大，处于高场，δ值小电子云密度小，处于高场，δ值大 ~0.9-C-CH 3 ~1.8-C=C-CH 3 ~2.1-COCH 3 ~3.0-NCH 3 ~3.7-OCH 3 11 10 9 8 7 6 5 4 3 2 1 0 -COOH -CHO Ar-H -C=C-H 常见结构的化学位移大致范围（要求熟记） (δ (δppm) 推断化合物的结构（含1H核基团的结构）（二）峰面积: 磁等同质子的数目——用积分曲线面积（高度）表示（三）峰裂分及偶和常数: 磁不等同两个或两组1H核在一定距离内相互自旋偶合干扰，发生的分裂所表现出的不同裂分符合n+1 规律 ( n = 磁等同质子的数目) 用偶合常数（J）表示峰裂分的数目峰裂分的距离不同系统偶合常数(J Hz) 大小 s 单峰d 双峰t 三重峰q 四重峰m 多重峰芳环 J 邻6~10Hz J 间0~3Hz J 对0~1Hz 双键 J 顺7~11 Hz J 反12~18 Hz 饱和烃类相邻碳原子上质子偶合常数的大小与两个氢原子之间的立体夹角θ有关

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