Effect of Microstructure on Impact Wear Resistance Impact Fatigue Resistance and of Medium Cr-Si Cast Iron

A great amount of iron grinding balls in tube mills have been consumed. Under this impact abrasive wear working condition, the failure of wear resistant alloying white irons grinding balls is mainly caused by fatigue spalling. The impact wear resistance of martensitic high chromium cast iron （Cr of 15%） is not high sometimes, but its cost is not low. Thus, medium Cr-Si wear resistant cast iron is recommended. The influence of the iron on impact fatigue resistance and impact wear resistance is pronounced. Ball-on-ball impact fatigue test and high stress impact wear test of the grinding balls have been carried out. The results show that the impact fatigue resistance （IFR） and impact wear resistance （IWR） of medium Cr-Si cast iron are superior to those of martensitic high chromium cast iron （Cr of 15%）. The main reasons are that （1） the stress in medium Cr-Si cast iron is released in the as-cast state; （2） the matrix is fine pearlite with better toughness and plasticity; （3） the pearlite is more stable compared with a retained austenite under repeated impact load and less phase transformation can take place; （4） high silicon content im- proves the morphology of eutectic carbide; （5） there is no seeondary carbide which results in less crack sources. All these factors are beneficial to improvement of impact fatigue spalling resistance. The eutectic carbide M7C3 is the main constituent to resist wear.     

Impact Wear Properties of Metal-Plastic Multilayer Composites Filled with Glass Fiber Treated with Rare Earth Element Surface Modifier

Ｍｅｔａｌ ｐｌａｓｔｉｃｍｕｌｔｉｌａｙｅｒｃｏｍｐｏｓｉｔｅｓ ,ｗｈｉｃｈａｒｅｃｏｍｐｏｓｅｄｏｆａｓｔｅｅｌｂａｃｋｉｎｇ ,ａｍｉｄｄｌｅｌａｙ ｅｒｏｆｓｉｎｔｅｒｅｄｐｏｒｏｕｓｂｒｏｎｚｅａｎｄａｓｕｒｆａｃｅｌａｙｅｒｃｏｎｓｉｓｔｉｎｇｏｆａｍｉｘｔｕｒｅｏｆｐｏｌｙｔｅｔｒａｆｌｕｏ ｒｏｅｔｈｙｌｅｎｅ (ＰＴＦＥ)ａｎｄｆｉｌｌｅｒｓ ,ｐｏｓｓｅｓｓｍａｎｙｇｏｏｄｐｒｏｐｅｒｔｉｅｓｏｆｔｈｅｏｒｉｇｉｎａｌｍｅｔａｌｓａｎｄｐｌａｓ ｔｉｃｓ,ｓｕｃｈａｓｈｉｇｈｍｅｃｈａｎ…     

Effects of Rare Earths on Toughness of 31Mn2SiRE Wear-Resistance Cast Steel

The toughness of 31Mn2SiRE wear-resistance cast steel were increased by means of RE compound modification and high temperature austenitizing. The results show that the microstructures can be refined, needle and network ferrite are eliminated, the dislocation density and the quantity of dislocated martensite are increased remarkably, and the shape and distribution of inclusions are improved by the addition of RE. Therefore, the mechanical properties of the modified steel can be greatly increased, especially the toughness (αK) by 44%, yield strength (σs) by 10%, and elongation (δ5) by 42%.     

Tensile Properties of Surface-Treated Glass Fiber Reinforced PTFE Composite with Rare Earth Elements

The optimum amount of rare earth elements (RE) for treating glass fiber surface and its effect on the tensile properties of glass fiber reinforced polytetrafluoroethylene (GF/PTFE) composites were investigated. The tensile properties of GF/PTFE composites with different surface treatment conditions were measured. The fracture surface morphologies were observed and analyzed by SEM. The results indicate that rare earth elements can effectively promote the interfacial adhesion between the glass fiber and PTFE, owing to the effects of rare earth elements on the compatibility. The tensile properties of GF/PTFE composites can be improved considerably when the content of RE in surface modifier is 0.2%-0.4%,and the optimum performance of GF/PTFE composites is obtained at 0.3 % RE content.     

Effect of Rare Earths on Tribological Properties of Carbon Fibers Reinforced PTFE Composites

Carbon fibers （CF） were surface treated with air-oxidation and rare earths （RE）, respectively. The effect of RE surface treatment on tensile strength and tribological properties of CF reinforced polytetrafluoroethylene （PTFE） composites was invest/gated. Experimental results revealed that RE was superior to air ox/dation in improving the tensile strength, elongation, and the tensile modulus of CF reinforced PTFE （CF/PTFE） composite. Compared to the untreated and air-oxidated CF/PTFE composite, the RE treated composite had the lowest friction coefficient and specific wear rate under a given applied load and reciprocating sliding frequency. The RE treatment effectively improved the interfacial adhesion between CF and PTFE. With strong interfacial coupling, the carbon fibers carried most of the load, and direct contact and adhesion between PTFE and the counterpart were reduced, accordingly the friction and wear properties of the composite were improved.     

Wear-Resistance Performance of ZA-27 Alloys Reinforced by Rare Earth Compounds

In order to further improve wear-resistanceof the ZA-27 alloy and widen its applieationfields, St phase is added in the alloy[' '21. ButSt phase seriously cuts apart the alloy matrix.It not only decreases high toughness of the alloy, but also is harmful to its wear-resistance.On the basis of the researches in foregoing periodical on Zn-based alloy reinforced by Stphase and the inLfluence of RE on the high temperature mechanical properties of the ZA-27 alloy["'j, this paper deals with the e…     

Effects of Rare Earths on Properties and Microstructure of Automotive Friction Materials

Rare earth compounds as modifiers used widely in modern friction materials can enhance the interracial binding of constituents of materials and improve the comprehensive properties of materials evidently. However, there are still few reports on application of rare earth in automotive friction materials. In order to study the effect mechanism of rare earths in friction materials, a rare earth compound was selected as additive and the effects of materials doped with or without rare earth on friction and wear properties of materials were studied. The microstructure and worn surface morphology were observed by scanning electron microscopy and the macro performance was discussed. Worn surface element constitution of materials was analyzed by energy dispersive spectroscopy. Effect mechanism of rare earths on friction and wear behaviors of friction materials were discussed. The results show that doping rare earths in friction materials can stabilize friction Coefficient, lower the wear rate of materials and increase the impact strength of materials. The flexibility and fracture resistance of materials is greatly improved. Worn surface of materials doped with rare earth is compact and the surface adhesion is greatly enhanced.     

Improving Corrosion Resistance of Cf/Mg Composites using Rare Earth Conversion Coatings

The surface of carbon fiber reinforced Mg matrix (Cf/Mg) composites was modified by treatment of rare earth conversion coating, and nontoxic, non-pollution Ce conversion coatings were prepared. The effect of the coatings on corrosion behaviors of composites was investigated by electrochemical polarization technology and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution. The higher Ecorr and lower icorr were obtained by Ce conversion coatings. EIS results showed that the higher values of R2 were obtained by treatment containing CeCl3, the high corrosion resistance occured in treatment containing CeCl3, the low corrosion resistance in uncoating sample, the coating of treatment containing Ce(NO3)3 was medium. The microstructure of Ce conversion coatings was observed by scanning electron microscopy (SEM), and the elements of corresponding for coatings was characterized by energy dispersive spectrometer (EDS). The micro-cracks and Ce-riched spherical particles were characteristics of these coatings.     

钨对AlN基复相材料微波衰减性能影响的研究

以AlN和W为原料，Y203为烧结助剂，在1850℃的N2气氛下热压烧结制备AlN-W复相衰减材料。运用XRD，SEM，网络分析仪等测试手段，研究了W含量、制备工艺对材料的显微结构、相组成、烧结性能及微波衰减性能的影响。结果表明，AlN-W复相衰减材料的衰减量随W含量的增加而增加，当W含量低于柏％时呈现选频衰减特性，而当W含量继续增加到50％时呈现良好的宽频衰减，且衰减量最高达到-1．9dB。探讨了AlN-W复相衰减材料的主要衰减机制。     

Effect of Rare Earth Additives on Chrome-Plating Quality

Electroplatingisoneofthetraditionalprocessesof decorationandsurfaceprotection.Boththeelectroplate principleandprocessparameterscanformacomplete setofsystem.However,therestillexistsixmostseri ousproblemssuchasthepoorcombinationstrengthof electroplatecoatin…     

Review on Application of Rare Earth Polishing Powders in Glass Polishing

The paper reviewed different explanations to the mechanism of glass polishing, the practices of glass polishing and the preparation of polishing powders, addressed the growth mechanism of CeO2 crystals, summarized the roles of rare earth elements in glass polishing and the factors that may influence the polishing effects, and specified the existing problems in glass polishing.