STUDIES ON FRICTION AND WEAR OF ALUMINUM ALLOY BASED COMPOSITES IN CORROSIVE ENVIRONMENTS

在湿空气、离子交换水、盐溶液和机油中进行单向和往复滑动条件下的摩擦磨损试验，研究铝合金（JIS AC8A）基氧化铝短纤维和空心二氧化硅颗粒增强复合材料在腐蚀环境中的摩擦磨损特性。从复合材料与不锈钢接触的单向滑动磨损试验结果来看，二氧化硅颗粒增强复合材料在湿空气中的严重磨损率高于与其他材料相比，因为二氧化硅颗粒在高负载下会破裂。低负荷时轻度磨损率较低，因为颗粒承担了部分负荷，从而提高了耐磨性。在离子交换水和盐溶液中，严重磨损和轻度磨损之间的过渡载荷比在湿空气中高约十倍。轻度磨损率几乎与 AC8A 相同，表明未发现对增强材料产生有害作用。与 AC8A 相比，氧化铝短纤维增强复合材料在湿空气中的耐磨性在轻度磨损状态下有所提高，但在所有环境中的高负载下比其他材料更差，因为增强材料的碎片表现出磨损作用。在水溶液中耐磨性比AC8A下降更多，表明增强材料的有害作用很明显。复合材料与轴承钢球在湿空气中往复滑动的摩擦磨损试验结果表明，复合材料在低载荷下的耐磨性优异。但复合材料的耐磨性与AC8A没有太大差异，只是钢球在高载荷下磨损较多。与其他材料相比，氧化铝-短纤维增强复合材料在机油中的耐磨性非常好。即使在高负载下，复合材料磨损和钢球损坏也会略有增加。二氧化硅颗粒增强复合材料在低载荷下表现出与氧化铝短纤维复合材料相当的耐磨性。然而，在高负载下，由于二氧化硅颗粒的破碎，磨损迅速增加，其碎片加速了钢球的损坏。三种材料的摩擦系数μ在机油中的较低负载范围内约为0.05，并随着负载达到50N以上的0.1附近的恒定值而增加。另一方面，在湿空气中μ约为0.5-0.9，按AC8A、氧化铝短纤维和二氧化硅颗粒增强复合材料。原因是由于嵌入接触表面的增强材料碎片产生的犁耕作用产生了摩擦阻力。较少的

Friction and wear tests under unidirectional and reciprocating sliding conditions were conducted in wet air, ion-exchanged water, saline solution, and machine oil to investigate the friction and wear characteristics of aluminum alloy (JIS AC8A) based alumina-short-fiber and hollow-silica-particle reinforced composites in corrosive environments.From the test results of unidirectional sliding wear of the composites in contact with a stainless steel, the rate of severe wear for the silica-particle reinforced composite in wet air is higher than the rate of other materials because the silica particles are fractured at high loads. The rate of mild wear is low at low loads because the particles bear a part of the load resulting in the improvement in the wear resistance. The transition load between severe and mild wear is about ten times higher in ion-exchanged water and saline solution than in wet air. The rate of mild wear is almost the same as that of AC8A,indicating no deleterious action o … More f the reinforcing material to be found.The wear resistance of the alumina-short-fiber reinforced composite in wet air is improved in the mild wear regime as compared with that of AC8A,however, is worse at high loads than other materials in all environments because the fragments of the reinforcing material exhibit abrasive action. The wear resistance is more decreased than AC8A in the aqueous solutions, indicating that the deleterious action of the reinforcing material is evident.The friction and wear test results of the composites against a bearing steel ball under reciprocating sliding in wet air reveal that the wear resistance of the composites are excellent at low loads. However, there is no great difference in wear resistance between the composites and AC8A with much wear of the steel ball at high loads.The wear resistance of the alumina-short-fiber reinforced composite is very good in machine oil as compared with other materials. A slight increase in the composite wear and the steel ball damage is seen even at high loads. The silica-particle reinforced composite manifests the wear resistance equivalent to that of the alumina-short-fiber composite at low loads. However, the wear rapidly increases at high loads due to the fracture of the silica particles, whose fragments accelerate the damage of the steel ball.The coefficients of friction mu of three materials are about 0.05 within a lower load range in machine oil and increase with load up to a constant value near 0.1 above 50N.On the other hand, the mu is about 0.5-0.9 in wet air and higher in the ascending order of AC8A,alumina-short-fiber, and silica-particle reinforced composites. The reason is that the plowing action due to the fragments of the reinforcing material embedded on contact surfaces exerts frictional resistance. Less