The wear performance of fine grain alumina ball adding diopside as fluxing agent are reported for the first time in this paper. The ball (average grain size 3 mum) exhibits excellent toughness and low wear rates. Plou...The wear performance of fine grain alumina ball adding diopside as fluxing agent are reported for the first time in this paper. The ball (average grain size 3 mum) exhibits excellent toughness and low wear rates. Ploughing grooves and traces of micro-cutting occur at the place with no pore. And the wear process is mainly caused by plastic deformation mechanism. Yet, the ordinary alumina balls (average grain size 6 and 15 mum) are brittle and the wear rates are high. The intergranular and transgranular dropping pits occur, and the wear process in mainly caused by brittle fracture mechanism.展开更多
Quantum-chemical calculations of polyatomic clusters simulating a boundary between grains in a surface layer of steel were carried out. Along with iron atoms the clusters contain atoms of alloying and impurity element...Quantum-chemical calculations of polyatomic clusters simulating a boundary between grains in a surface layer of steel were carried out. Along with iron atoms the clusters contain atoms of alloying and impurity elements which appear on the boundary due to grain boundary segregation or intergrain diffusion. The influence of the chemical composition of a segregate on the strength of coupling between grains and, eventually, on steel wear resistance is analyzed. Results obtained show that the degree of the strength of binding of segregated atoms with atoms of iron in a metal surface layer is an essential factor influencing wear resistance. It is found that the dependence of energy of binding of atoms of different elements with grain surface on the atomic number complies with the periodic law. This fact can be considered as a theoretical base for the prognostication of strength properties of steel with different composition of alloying and impurity elements. Potential energy curves corresponding to the movement of atoms on iron surface are studied. They can be useful for design of the composition of multi-layer coats on steel.展开更多
TiC/ZA43 composites were fabricated by XD TM and stirring casting techniques. The tribology properties of the unreinforced ZA43 alloy and the composites were studied by using a block on ring apparatus. Experimental re...TiC/ZA43 composites were fabricated by XD TM and stirring casting techniques. The tribology properties of the unreinforced ZA43 alloy and the composites were studied by using a block on ring apparatus. Experimental results show that the incorporation of TiC particles improves the microstructure of ZA43 matrix alloy. The coefficient of friction μ and the width of worn groove decrease with the increase of TiC volume fraction φ (TiC). The width of worn groove and μ of the composite during wear testing increase with increasing the applied load. Metallographic examinations reveal that unreinforced ZA43 alloy has deep ploughing grooves with obvious adhesion phenomenon, whereas TiC/ZA43 composites have smooth worn surface. Delamination formation is related to the fatigue cracks and the shear cracks on the surface. [展开更多
The effect of rare earth （Re） and titanium （Ti） multi-modification on the impact wear behavior of Mn-B high-Si bainitic cast steel was investigated systematically. The experiments show that the impact wear resista...The effect of rare earth （Re） and titanium （Ti） multi-modification on the impact wear behavior of Mn-B high-Si bainitic cast steel was investigated systematically. The experiments show that the impact wear resistance can be improved greatly with the addition of Re and Ti. Its wear loss is only about 1/3-1/2 as large as that of the unmodified bainitic cast steel. By the Re/Ti modification, coarse dendrite grains and bainitic/martensite duplex structure have been refined effectively, and the impact toughness of the bainitic cast steel is nearly tripled （10 mm×10 mm×55 mm, with unnotched sample）. Consequently, the modified bainitic cast steel possesses good wear resistance under high im- pact. For both modified and unmodified bainitic cast steels, high hardness white layer and deformed zone are developed beneath the worn surface under the high impact wear, but the formation and propagation of cracks are different for these bainitic casting steels. Different mod- els for the formation and propagation of cracks for both modified and unmodified bainitic cast steels under high impact wear are proposed.展开更多
The phenomenon that the hard abrasive grains repeatedly cut the surface material of the parts during wear is very common in wear. In order to study the influencing factors of mechanical damage, based on the three-body...The phenomenon that the hard abrasive grains repeatedly cut the surface material of the parts during wear is very common in wear. In order to study the influencing factors of mechanical damage, based on the three-body abrasive wear, this paper discusses the wear of the secondary cutting abrasive. Firstly, the secondary wear model of the hemispherical abrasive grain on the friction pair surface is established. Secondly, the simulation experiment is carried out on the secondary scratching of the abrasive wear on the surface of the part. Next, the equivalent strain data and the equivalent stress data obtained by the experiment are subjected to secondary friction analysis. The final results show that the secondary friction damage of the hemispherical abrasive grain is greater than one wear.展开更多
基金Funded by Hubei Province Key ScientificTechnological Development Foundation (No.951P0301).
文摘The wear performance of fine grain alumina ball adding diopside as fluxing agent are reported for the first time in this paper. The ball (average grain size 3 mum) exhibits excellent toughness and low wear rates. Ploughing grooves and traces of micro-cutting occur at the place with no pore. And the wear process is mainly caused by plastic deformation mechanism. Yet, the ordinary alumina balls (average grain size 6 and 15 mum) are brittle and the wear rates are high. The intergranular and transgranular dropping pits occur, and the wear process in mainly caused by brittle fracture mechanism.
文摘Quantum-chemical calculations of polyatomic clusters simulating a boundary between grains in a surface layer of steel were carried out. Along with iron atoms the clusters contain atoms of alloying and impurity elements which appear on the boundary due to grain boundary segregation or intergrain diffusion. The influence of the chemical composition of a segregate on the strength of coupling between grains and, eventually, on steel wear resistance is analyzed. Results obtained show that the degree of the strength of binding of segregated atoms with atoms of iron in a metal surface layer is an essential factor influencing wear resistance. It is found that the dependence of energy of binding of atoms of different elements with grain surface on the atomic number complies with the periodic law. This fact can be considered as a theoretical base for the prognostication of strength properties of steel with different composition of alloying and impurity elements. Potential energy curves corresponding to the movement of atoms on iron surface are studied. They can be useful for design of the composition of multi-layer coats on steel.
文摘TiC/ZA43 composites were fabricated by XD TM and stirring casting techniques. The tribology properties of the unreinforced ZA43 alloy and the composites were studied by using a block on ring apparatus. Experimental results show that the incorporation of TiC particles improves the microstructure of ZA43 matrix alloy. The coefficient of friction μ and the width of worn groove decrease with the increase of TiC volume fraction φ (TiC). The width of worn groove and μ of the composite during wear testing increase with increasing the applied load. Metallographic examinations reveal that unreinforced ZA43 alloy has deep ploughing grooves with obvious adhesion phenomenon, whereas TiC/ZA43 composites have smooth worn surface. Delamination formation is related to the fatigue cracks and the shear cracks on the surface. [
文摘The effect of rare earth （Re） and titanium （Ti） multi-modification on the impact wear behavior of Mn-B high-Si bainitic cast steel was investigated systematically. The experiments show that the impact wear resistance can be improved greatly with the addition of Re and Ti. Its wear loss is only about 1/3-1/2 as large as that of the unmodified bainitic cast steel. By the Re/Ti modification, coarse dendrite grains and bainitic/martensite duplex structure have been refined effectively, and the impact toughness of the bainitic cast steel is nearly tripled （10 mm×10 mm×55 mm, with unnotched sample）. Consequently, the modified bainitic cast steel possesses good wear resistance under high im- pact. For both modified and unmodified bainitic cast steels, high hardness white layer and deformed zone are developed beneath the worn surface under the high impact wear, but the formation and propagation of cracks are different for these bainitic casting steels. Different mod- els for the formation and propagation of cracks for both modified and unmodified bainitic cast steels under high impact wear are proposed.
文摘The phenomenon that the hard abrasive grains repeatedly cut the surface material of the parts during wear is very common in wear. In order to study the influencing factors of mechanical damage, based on the three-body abrasive wear, this paper discusses the wear of the secondary cutting abrasive. Firstly, the secondary wear model of the hemispherical abrasive grain on the friction pair surface is established. Secondly, the simulation experiment is carried out on the secondary scratching of the abrasive wear on the surface of the part. Next, the equivalent strain data and the equivalent stress data obtained by the experiment are subjected to secondary friction analysis. The final results show that the secondary friction damage of the hemispherical abrasive grain is greater than one wear.
