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As the raw material for producing molybdenum products, the quality of molybdenum powder such as purity, microstructure, particle size and distribution, has great influence on the microstructure of molybdenum products, which will affect its performance. In this study, the effect of potassium element content and crystal form of ammonium tetramolybdate and reduction conditions on the properties of molybdenum powder was studied. The results show that under the same reduction conditions, the particle size of molybdenum powder obtained by the reduction of high potassium ammonium tetramebolybdate is larger than that obtained by the reduction of low potassium ammonium tetramebolybdate. The particle size distribution of molybdenum powder obtained by the reduction of ammonium tetramebolybdate with mixed crystal form (α-type and β-type) is wider, while that obtained by the reduction of ammonium tetramebolybdate with single crystal form (β-type) is narrower and the particle size is more uniform. The higher the reduction temperature is and the lower the hydrogen flow rate is, the larger the particle size of molybdenum powder will be. The agglomeration degree of molybdenum prepared by β-type ammonium tetramolybdate is lighter than that prepared by ammonium tetramolybdate with mixed crystal form (α-type and β-type), and its sieving rate is higher.

The microstructure of Cu-Al composite plate based on the cast-rolling technology is investigated by scanning electron microscope, x-ray diffractometer, energy-dispersive spectroscopy and transmission electron microscopy. The interfacial structure is analyzed by high-resolution transmission electron microscopy. The results show that the copper–aluminum composite plates with oxygen-freed metallurgical bonding interface by cast rolling. The interfacial intermetallic is CuAl2 with a thickness of 0.35 μm. There is a crystallographic orientation relationship between the matrix Al and CuAl2. The (200) crystal plane of CuAl2 parallels to the ($$11\bar{1}$$) crystal plane of Al with the mismatch of 0.22.

Ti-6Al-4V-1.5Mn alloy was prepared by powder metallurgy and solid solution aging treatment. Effect of composition segregation on properties of the titanium alloy was eliminated, and microstructure and the mechanical properties of the alloy were studied. Results show that the microstructure of Ti-6Al-4V-1.5Mn is composed of homogeneous α + β phase, and the optimal mechanical properties of the alloy are obtained when the solution temperature is 950 °C and the aging temperature is 460 °C. Analysis of the fracture illustrates that a small amount of dimple was found in the section and the fracture of the material was quasi-cleavage fracture.

In order to explore the compressive properties of aluminium matrix composite reinforced with middle content SiC particles, hot compression behavior of 30%SiCp/2024A1 composite was investigated using Gleeble-1500 system at a temperatures range from 350 to 500°C and strain rates from 0.01 to 10 s−1. The associated structural changes were studied by OM, SEM and TEM observations. The results show that the true stress–true strain curves exhibited a peak stress at a small strain (

High-Cr cast-penetrated layer contained nanometer ceramic particles was formed on the surface of the medium carbon steel ZG250-470 by adding nanoTiN intermediate alloy powder to cast-penetrated agent. Microstructure and wear resistance of the strengthened cast-penetrated layer were studied. The results showed that: compared with not adding intermediate alloy, there were finer and more uniform microstructure and better high temperature and high speed wear performance of strengthened cast-penetrated layer strengthened by nanoTiN intermediate alloy. Strengthening effect would be best by adding the intermediate alloy containing rare earth. By adding intermediate alloy containing Ni, the best high temperature wear resistance of cast-penetrated layer could be obtained.

The YBCO powder was prepared by oxalic acid precipitation method and consequent annealing. The correlation between pH values of oxalic acid solution and the precipitation percentage of precursors were analysed based on thermodynamics analysis. The differential scanning calorimetryanalysis (DSC) was used to confirm the synthetic technological parameter. The phases of powder in each process were investigated by XRD. The microstructures of each powder were tested by SEM and TEM. The mean grain size was calculated by the scherrer’s equation. The test results indicated that the YBCO powder with high purity, less impurities, smaller particle, but severe agglomeration, was Y123 when annealing at 900°C. However, adding dispersants could effectively solve the severe agglomeration. The size of YBCO particles was nanosized and coincided with the calculation.

In the present work, rapidly solidified Al-21Si-0.8Mg-1.5Cu-0.5Mn alloys strips was prepared by melt-spinning technique. The microstructure morphology and phase structures of experimental alloy were characterized by means of scanning electron microscopy (SEM), transmission electric microscopy (TEM) and XRD technique. The results show that the grains were refined and the micro-nanocomposite structural were formed under rapid solidification. The nucleation and growth of primary silicon were suppressed and primary silicon could not deposited, meanwhile, α-Al phase was nucleated which prior to eutectic. The microstructure of the Al-21Si alloy was composed of micro-nanostructured α-Al phase and feather-needles-like eutectic α-Al+β-Si phase. The hypereutectic Al-21Si alloy showed the hypoeutectic microstructure. The rapidly solidified Al-21Si alloy microstructure formation mechanism has also been discussed.

In this paper, metallographic structures, hardness, wear resistance, impact toughness and impact fractures were adopted to study effects of different quenching methods (air cooling + fog cooling) and tempering temperatures on microstructure and mechanical properties of 75Cr-Mo wear-resisting cast steel. The results reveal that quenching stress could be decreased effectively by using "air cooling + fog cooling" comparing with water quenching, thus avoiding initiation of micro crack. the microstructure of the quenched steel mainly comprises pearlite in addition to a little martensite and ferrite. M23C6 carbides, which have no crystal orientation with the matrix, disperses in the matrix. A hardness of 401 HBW and impact toughness of 35 J/cm2 were obtained for the steel when quenched after insulation for 2 hour at 880℃.

Ti-Al composite plate is prepared by cast rolling method, then annealing treatment of different processes is carried out on it. Mechanical properties and hardness of the composite plate under different annealing processes are tested by precision universal testing machine and micro hardness tester. Scanning electron microscope (SEM) is used to observe interface layer morphology, tensile fracture morphology. The results show that: after annealing at 450℃ for 3 h, good metallurgical bonding layer is formed by diffusion of Ti and Al. The thickness of the interface layer is about 2.5 μm. At this time the tensile strength is 103 MPa and elongation rate is 53%. When the two kinds of metal are stretched, cracking degree is the least and comprehensive performance is the best.

The hot deformation behaviors of 30%SiCp/2024 aluminum alloy composites was studied by hot compression tests using Gleeble-1500 thermomechanical simulator at temperatures ranging from 350-500°C under strain rates of 0.01-10 s-1. The true stress-true strain curves were obtained in the tests. Constitutive equation and processing map were established. The results show that the flow stress decreases with the increase of deformation temperature at a constant strain rate, and increases with the increase of strain rate at constant temperature, indicating that composite is a positive strain rate sensitive material. The flow stress behavior of composite during hot compression deformation can be represented by a Zener-Hollomon parameter in the hyperbolic sine form. Its activation energy for hot deformation Q is 183.251 kJ/mol. The optimum hot working conditions for this material are suggested.

The grain size of W-Cu nanocomposites would greatly affect the density of W-Cu alloy. In this work, W-Cu oxide nanocomposite powders were prepared by sodium tungstate and copper nitrate via hydrothermal method, and W-Cu nanocomposite powders were obtained by subsequently co-reduction process. The characterization of W-Cu nanocomposite powders were carried out by X-ray diffraction (XRD), scanning electron microscope (SEM), energy spectrum analysis (EDS) and transmission electron microscope (TEM). The results indicated that hydrothermal method was a good method for the preparation of W-Cu oxide nanocomposite powders. W-Cu nanocomposite powders, whose grain size was about 70nm and distributed uniformity, were manufactured by co-reduction process.

The hot deformation behaviors of 30%SiCp/2024 aluminum alloy composites was studied by hot compression tests using Gleeble-1500 thermomechanical simulator at temperatures ranging from 350-500 °C under strain rates of 0.01-10 s-1. The true stress-true strain curves were obtained in the tests. Constitutive equation and processing map were established. The results show that the flow stress decreases with the increase of deformation temperature at a constant strain rate, and increases with the increase of strain rate at constant temperature, indicating that composite is a positive strain rate sensitive material. The flow stress behavior of composite during hot compression deformation can be represented by a Zener-Hollomon parameter in the hyperbolic sine form. Its activation energy for hot deformation Q is 153.251 kJ/mol. The optimum hot working conditions for this material are suggested.

The influences of the impact angle and the corrosive agent acidity on low-chromium and nickel contained cast iron were studied in the behavior of erosion wear. The wear rule was summarized and the mechanics of the erosion wear behavior were analyzed in this thesis. Erosion wear experiments were carried on MCF-30 erosion test machine, and then the structure and surface morphology of the samples were analyzed by Scanning Electron Microscopy (SEM). The results showed that the alloy carbide (Fe, Cr)3C was generated by a kind of reticulate distribution in the matrix after oil quench at 960°C and temper at 250°C. The continuous and homogeneous distribution, just like the skeleton of the material, enhanced the wear resistance. The shape of erosion wear curve was M at different impact angles. The biggest wear rate occurred at a 60-degree impact angle. The erosion wear property was greatly affected by the strong acid, but it can be ignored when pH3.

Cu-3wt. %MoS2-7wt. %Mo and Cu-3wt. %MoS2 composites were prepared by repressing, re-sintering and vacuum hot pressing, respectively. Microstructures were characterized by optical metallographic microscope, EDS, SEM and X-ray diffraction analysis, respectively. The micro hardness, electric conductivity and density of samples were separately measured as well. Results show that the micro hardness of Cu-3wt. % MoS2-7wt. % Mo composites is about 33.3% higher than that of Cu-3wt. %MoS2 composites. The increase in micro hardness is attributed to the presence of Mo. The electric conductivity of Cu-3wt. %MoS2 and Cu-3wt. %MoS2-7wt. % Mo prepared by vacuum hot pressing were 80.6 % and 63.8% IACS, respectively, which is an increase compared with values of 80.2 % and 57.3% IACS of samples obtained by repressing and re-sintering.

Based on the traditional Mn13, the super-high manganese steel Mn18 was melted by means of adjusting the amount of C, Mn, adding a certain amount of alloying elements Cr, Mo etc and modification. The results show that with low-impact energy abrasive wear for 60 minutes, the wear resistance of super-high manganese steel Mn18 was greatly improved by contrast with that of Mn13, and the hardness of wear surface was increased slowly with the elapse of the wear time. However, under the high impact energy, the wear resistance of Mn18 is 1.5 times as high as that of Mn13, and the hardness of wear surface was increased to HB440 in a short time. The main wear forms were: cutting, gouging wear and plastic deformation. Typical TEM morphologies of subsurface wear structure consist mostly of high density dislocations, deformation bands.

The effects and the mechanisms of namo TiN on the high chromium cast iron are studied, the material has been prepared through infiltration casting and addition of high carbon ferrochrome powder and nano TiN powder. The alloy is formed on the surfaced of guide plate, and the wear resistance of alloy have been studied by means of SEM, XRD micro-analysis and wear-resistant performance. The grain size and the type of carbide in the organization are affected by nano TiN, and the wear resistance of carbon chromium alloy layer is affected by the type of carbide; when the addition of nano TiN is 1% (wt), the grain size is apparently refined, overeutectic primary M7C3 in the hypereutectic is precipitated uniformly in considerable amounts, therefore the wear resistance of alloy can be improved effectively.

α-SiC particles have been processed with surface treatment of high-temperature calcination and water washing technology. SiCp/Al-30Si composite has been prepared in the vacuum hot extrusion process. The powder morphology and specimens microstructure have been observed using scanning electron microscopy, the phase of SiC has been analyzed using the X-ray diffraction. Meanwhile, the tensile strength and thermal expansion coefficient of the composite have been tested. The effects of the morphology of the SiC particles, tensile strength and thermal expansion coefficient have been studied on composite microstructure. The consequences show that, after the surface treatment SiCp/Al-30Si composite，the interfaces combined with matrix are in a better condition and less holes, the tensile strength of composite materials has been improved significantly, the coefficient of thermal expansion becomes lower than before.

Al-50Si can be fabricated with a method in which air-atomization is followed by vacuum canning hot-pressing process. In order to improve the mechanical character and the physical property，the treatment of high-energy milling are used in the pretreatment of the powder of Al-50Si.The microstructure，density ,coefficient of thermal expansion are analyzed by scanning electron microscope(SEM) and thermal physical tester. It was found that the silicon grain was refined, the density and strength was improved when high silicon alloy powders were treated by high-energy ball milling.

In this research, different frictions were settled to study the wear resistance of HT250, RuT15, RuT75 and QT500 according to the wear failure situation in automobile brake drum. And the relationship between wear mechanism, microstructure and mechanical properties were discussed. It can be seen from the friction and wear experiment that, under different friction and wear conditions, both of RuT35 and QT500 have the best wear resistance property while HT250 has the worst wear resistance property. With the increase of lord, the brake torque and friction coefficient of RuT35 stays unchangeable, showing well brake ability. With the increase of lord, the brake ability of HT250 was getting better, while QT500 showing the opposite. SEM was used to analyze the wear morphology, the results show that: the abrasive wear and adhesion wear are presented mainly. HT250 has a bad surface quality while QT500 and RuT15 have a bad surface quality. Generally speaking, RuT15 is the best material to made brake drum, in the consideration of were resistance and braking stability.

The ZGMn13Cr2 reinforced by the nano-SiC master alloy is investigated in this paper. The nano-SiC master alloy which comprise nano-SiC powders and other metal powders are prepared, then the nano-SiC master alloy is added into the ZGMn13Cr2 samples under industrial conditions. The morphology and mechanical properties of the samples are studied. The results show that: When the nano-SiC Master Alloy is added into the sample, the microstructure of ZGMn13Cr2 improve significantly and the absorbed energy of the samples increased obviously.

The SiCp/Al-30Si composite material was prepared by hot-pressing. The microstructure was characterized by means of optical microscope and SEM, the thermal expansion performance was tested by PYC-Ⅲ Thermal Expansion Coefficient Tester. It was researched that the influence of SiC particle size and manufacture technology on the microstructure and thermal expansion coefficient. Results show that shortening soaking time decreases the number and the size of the nascent and precipitating Si particles, enlarges the CTE of the composite; lager pressure is beneficial to reduce the CTE of the composite, and the larger the pressure is, the more compact microstructure is and the less number of holes are. Thermal expansion performance of the composite was influenced by SiC particle size, distribution of matrix phase, trait of interface combination and the holes.

The numerical solidification simulation for gear ring steel casting has been made, and the location and reasons forming casting defects have been predicted by HUAZHU CAE software. Simulating result shows that the directional solidification and efficient feeding were maintained and the casting perfects can be realized by means of the computer simulation optimizing technological and rationally design of gating system, insulated risers, iron chill and compensating efficiently. After magnetic particle detection and ultrasonic inspection, the properties and microstructure of the Gear ring steel casting are in accord with the international standard.

In the present work, the Al-21Si-0.8Mg-1.5Cu-0.5Mn alloys composite modified by P+RE was prepared by metal mold casting. The tribological properties against steel under lubrication conditions were experimentaled. The wear morphology characteristics and subsurface microstructure was characterized by means of optical microscope and scanning electron microscope. The effects of Si particle morphology, size, quantity and distribution on tribological properties were investigated. The wear mechanism based on lubricant abrasion was discussed. The results show that the wear mechanism of experimental alloy are mainly abrasire wear and fatigue spalling.

The numerical simulation of temperature gradient in the solidification process for large bushing castings of zinc-base alloy was made with HUAZHU CAE/Inte-CAST10.0 software in this paper. Tendency and the position of shrinkage were predicted,and the effect of cooling water rate and cooling time on temperature gradient and shrinkage during the molten metal solidification was discussed. The results show that:seting chilled iron at bottom of bearing bush and using water-cooling metal core in inner cavity of casting simultaneously, can eliminated shrinkage hole and porosity.

By means of wear analysis of the wear-resistant steel used in the process, and adjust the wear-resistant steel composition, by adding alloying elements Cr, Mo and so on, optinlizing heat treatment technique, to get new wear-resistant steel. The HR-150A rock well hardness tester and JB-300B impact tester as well as SHIMADZUAG-I250KV on electronic tensile testing machine were used to test the mechanical properties of materials. In the test of friction and wear performance was done using the high temperature and high-speed friction of wear-testing maching (MMS-1G), and analysis of microscopy and the wear morphology by JSM-5610LV SEM．The results showed that: The hardness of new wear-resistant steel reaches HRC53, the impact toughness 23J/cm2, And at this moment, the sample matrix is the microstructure of small lath martensite and residual austenite.

In this paper ,the WC and high-Cr Cast Iron layer were obtained on the surface of ZG30Cr steel by casting-penetrating process, the organization and wear properties of penetrating layer were studied.The results show that the layer is dense, without pores, slag and other defects, the penetrating layer and substrate are metallurgical bonding. When 30 %WC and 70 % Cr-Fe with 100～120 mesh are added to permeability agent ,the penetrating layer has the best wear resistance, is 6.8 times the matrix materials. Keywords: The layer structure; Particle size; Wear resistance

In this paper , by SEM、EDS、XRD and Shimadzu AG-I250KN precision universal testing machine , the metallurgical structure, fracture appearance, the mechanical properties of the ZA303 under high temperature were systematically studied .The results shows that :The microstructure of ZA303 at room temperature are : α phase + (α＋η) eutectoid + ε phase + η phase. After adding modifying elements B、Ti in ZA303：the microstructure of the alloy is from gross dendrites to uniform equiaxed grains , the quantity, morphology and distribution of the (α + η) have greatly change: the quantity of (α + η) is less, from a continuous network to intermittent block, and its end become blunt, or even cylindrical horn and dispersed distribution; on the grain boundary, the size of ε phase become smaller and dispersed distribution, the number of mesh ε phase reduced but intermittent strips increased; adding B、Ti have a good effect of restraining Al element segregation，so the foundry defects decreased obviously. In the range of experimental temperature, the increase of ductility is large while the tensile strength is small: at the same time, the mechanical performances stability is better than that without modification.

This work aims to eliminate contamination of the surface of crucible with silicon carbide during fusion preparation sample of the X-ray fluorescence analysis used in relation to electroless Ni–P plating process on the surface of SiC crucible in the alkaline bath. The structure, morphology and component of the coated layers were clarified by means of XRD, SEM and EDAX. Also, the electrochemical measurements was carried out to characterize the reduction mechanism of Ni deposition. The bath compositions were nickel sulfate 20 g/L, sodium hypophosphite 30 g/L, sodium citrate 10 g/L，ammonium chloride 20 g/L, containing a mixed additives of thiourea, sodium lauryl sulfate and coumarin. The thickness of coating was 3.47 μm after plating for 15 min from this bath at 318 K. The coating is relatively dense and smooth and has a nodular surface morphology. The uniform Ni–P film is a mixture of microcrystalline of Ni5P4 and crystalline phases of Ni in the alkaline bath, with the components of 4.74%P and 95.26%Ni. The nickel deposition reaction occurs at -1.07 V appropriately with the peak current density of 32 mA/cm2 and the electrochemical deposition of nickel is mainly controlled by the electrochemical process.

In this paper, the Cu/MoS2/Mo composites were prepared by the powder metallurgy technology. The friction wear test was tested by the HST-100 High Speed Electric-tribometer. The microstructure and wearing surface morphology were examined by SEM and EDS. The electrical sliding wear behavior of the composites was discussed. The results indicated that the dense composites are obtained; the wear mechanisms of Cu/MoS2/Mo are mainly abrasive wear and adhesive wear with arc erosion; the effects of current intensity and sliding velocity on the wear property of the composites are complicated, and the composites show the best property when the current intensity is 60A and the sliding velocity is 40m/s.

In this study, Nd: CW CO2laser were used in LSA experiment on Steel C1045 with four different systems alloyed by Sub-Micron Ceramics, namely Ti+C, TiO2+C, TiC, Ti+V+C. The high hardness alloyed coating was prepared on the surface of Steel C1045 adopting laser alloying process for the ideal reinforced effect of surface that we expect. The microstructures of the four different alloy systems were analyzed by SEM. The microhardness and the friction coefficient of these laser alloying layers were examined, then the abrasion resistance and the main wear mechanism were summarized. According to the experimental results, comprehensive properties of Ti+V+C system were the most excellent in all systems.

In this paper,the effect of rare earth La on microstructures and properties of ZA30 alloy were studied . The result shows that The structure is refined and mechanical properties are improved by adding La to ZA30 alloy,the alloy have best structures and comprehensive mechanical properties when La content is 0.1%; Rich-La phases are metallic compound Cu2La,Al2La and LaZn and precipitate in blocky form ,its number and size increase with La; The abrasive resistance of ZA30 alloy is significantly improved when La is over 0.3%.

Mn18Cr2 steel is one of austenitic deformation strengthening steel. The existing form of TiN and its influence on the austenitic structure in the steel by adding small amounts of TiN nanoparticles are discussed in this study, which may provide some advices to explore new way to strengthen high manganese steel. The microstructures of Mn18Cr2 steel added small amounts of TiN nanoparticles are observed by Transmission Electron Microscopy (TEM). The results show that TiN nanoparticles exist in austenite and there have a very good match interface between the two phases, the crystal face relationship are {220}γ//{220}N, {422}γ//{422}N, (111)γ //(200)N , orientation relationship are γ// N, γ//N, [112]γ // [011]N, moreover, the relationship of (111)γ and (200)N is not only parallel but also coherent. Meanwhile, there are many high density dislocations, a small amount of stacking faults, twins and ε-martensite in the austenite due to the role of TiN nanoparticles.

Erosion wear experiments on Nickel-Chromium cast iron were tested by MCF-30 erosion test machine. The structure and surface morphology of these samples were analyzed by Scanning Electron Microscopy (SEM), Transmission Electron Microscope (TEM) and XRD. The influences of the impact angle and acidity on erosion wear property were analyzed. The discipline of the erosion wear property was discussed as well. The experimental results indicate that after oil quench at 960°C and temper at 250°C, the alloy carbide (Fe, Cr)3C which works as the wear resistance skeleton distributes uniformly in the matrix ; the shape of erosion wear curve is “M”. and the biggest wear loss is when the impact angle is 60°; the erosion wear property is affected greatly by the strong acid, but is little even can be ignored when pH≥3. The erosion wear mechanism of Nickel-Chromium cast iron is selective wear.

In this paper, based on ctual large-scale ball mill liners working conditions, effects of different quenching temperature and tempering temperature on the Cr-Mo steel performance, optimize the best heat treatment process.The use of sophisticated electronic universal tensile testing machine, and Rockwell hardness testing machine for testing mechanical properties of steel materials were tested; Using the MMS-1G-type high-temperature high-speed Friction and wear tester, the wear properties of steel samples were studied using JSM-5610LV scanning electron microscope study of the tensile test fracture surfaces of steel and the friction and wear morphology. The results show that: For the high carbon alloy steel, of which 870 °C 620 °C tempered quenched specimen extension rate of 7.0% area reduction rate of 9.5%.

The WC and high-Cr cast iron layer were obtained on the surface of ZG30 steel by infiltration casting process, so the surface alloying of ZG30 steel was realized. The microstructures and phase structures of penetrating layer were studied by SEM, TEM, XRD, the hardness of the test material was measured by the hardness tester, and the wear resistance was tested by wear test machine. The mechanism of alloyed layer forming was analyzed. The effects of WC contents on the wear resistance of alloyed layer were studied. The results show that the layer is dense, without pores, slag and other defects, the thickness of the alloyed layer is about 6-7mm, and the penetrating layer and matrix are metallurgical bonding. The maximum hardness of the alloyed layer surface is 820Hv. When the content of WC is 15%, the penetrating layer has the highest wear resistance which is 18.8 times as high as the matrix.

The influences of non-metallic inclusions on the quality and properties of the steel not only depended on the quantity of inclusions, but also on the type、shape、size、deformation behavior and distribution condition. By means of ANSYS finite element analysis software, the stress field distribution in the inclusions and the matrix around the inclusions are analyzed under the condition of different kinds of types、shapes、distributions with changeable load in heavy rudder arm steel castings, then micromechanics behavior of inclusions is investigated from angle of macro mechanics.

The influences of non-mentallic inclusions on the quality and properties of the steel are depended not only on the quantity of inclusions, but also on the type、shape、size、deformation behavior and distribution condition. The effects of lanthanide rare earth(RE) on the shape、size and distribution condition of inclusions in large rudder arm steel casting is investigated. It was proved that the shape and distribution of inclusions could be improved in the large rudder arm steel casting, and the plastic and toughness of the steel can be increased obviously by the rare earth modification. By means of ANSYS finite element analysis software, the stress field distribution around matrix was simulated, and the reaction mechanism of inclusions by modification was clarified.

The erosion wear experiments of low-chromium cast iron containing nickel were done by MCF-30 Erosion Abrasion Experimental Machine. The structure and surface morphology after erosive wear were analyzed by SEM and XRD. The results indicated that the distribution of carbide was reticular after tempering at 250and oil quenching at 960. The maximal erosion wear rate was appeared at 60 °erosion angle, high acid corrosion media have great influence on the abrasion resistance of experimental material and corrosion effects almost had no influence on the abrasion resistance of experimental material in the weak acid environment of pH≥3. The erosive wear mechanism of the experimental material was studied.

In this paper, the WC and high-Cr Cast Iron layer were obtained on the surface of ZG30Cr steel by casting-penetrating process, the organization and wear properties of penetrating layer were studied. The results show that the layer is dense, without pores, slag and other defects, the penetrating layer and substrate are metallurgical bonding. When 20 %WC and 80 % Cr-Fe with are added to permeability agent, the penetrating layer has the best wear resistance, is 11.3 times the matrix materials.

In order to improve the wear resistance of continuous casting crystallizer, Co-based alloy coatings were prepared on copper substrate by a pulsed Nd:YAG laser. Scanning electron microscopy, X-ray diffraction, microhardness and wear resistance testing were employed to study the microstructure and properties of the cladding coatings. The results show that the friction coefficient and wear mass loss of the cladded coating with the volumn ratio of Stellite X-40：TiC：CaF2=60：10：30 are both the smallest; the average microhardness of the cladded coating is 496.2HV0.2 which is about five times higher than that of the substrate.

The elastic-plastic finite element mechanical model of hypereutectic Al-Si alloy was established based on ANSYS software. When the Si particles were circle, trapezium, rectangle or triangle, the microstress of Al-Si alloy under the external load were simulated. When the size of Si particles changed from 25μm to 45μm, the stress of Si particles and matrix interface was calculated. The effects of morphology and size of Si particles and loads on micro-mechanics characteristic of alloy were analyzed. The results showed that: under the same load, triangle or wedge angle Si particles make the biggest stress in the matrix, trapezoidal particles make the second and the spherical particles make the smallest. With the increase of the load, the stress and the stress concentration of Si particles in the matrix was increased, the stress of wedge angle particle increases remarkably, but the stress of spherical particles increases slowly. With the increase of the size of Si particles, the stress and the stress concentration of Si particles in matrix are increased.

Using sub-micron WC/Co metal ceramic composite as coating materials for laser alloying experiments to prepare high hardness and wear resistance alloyed layer on the surface of 9CrSi. The microstructures of laser-alloyed coating were detected by SEM and XRD. The microhardness and wear-resistance of the coatings were also investigated. The results indicate that, the laser alloyed layer and substrate form a good metallurgical bonding. The analysis of SEM reveal that the alloyed layer can be divided into alloyed zone, heat affected zone and substrate zone. The alloyed zone is composed by martensite, netted dendrite carbides and small carbide particles, the netted dendrite carbides distribute in the martensitic and the small carbide particles dispersed in the gap of the netted dendrite. The heat affected zone is consisted of retained austenite and martensite. There is no significant change in the matrix zone.The coating has a high hardness of 900HV0.2 , and the abrasion loss of the alloyed coating is just one ninth of that of 9CrSi. The wear resisitance of the alloyed coating relative to the substrate 9CrSi has significantly improved.

Stellite 12/TiC/CaF2 composite coating has been successfully fabricated on copper substrate by a pulsed Nd:YAG laser system with preplacment powder bed to improve the absorbance of copper substrate to laser energy. Microstructures, phases and wear properties were studied by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), dry sliding wear tester. The results showed that the existence phases of Co-based solid solution, Cr4Ni15W, TiC, Cr23C6, CaF2 and Ti8C5. The morphology of titanium carbide is mainly spherical and exists in two forms, one is TiC and the other is Ti8C5. The microhardness of the layers reveals a gradient variation along the cross section of the LSA layers. The friction coefficient of the coating is oscillating around approximately 0.17 because CaF2 is a solid lubricant because of the lamellar structure and softness and Titanium carbide is hard. The dry sliding wear testing shows the wear resistance of as-receive copper is significantly improved by laser cladding Stellite 12/TiC/CaF2 composite coating.