Simultaneous measurement of corrosion and wear resistance of stainless steel modified by frictional reforming with aluminum oxide carrier particles under fretting conditions in seawater

The purpose of this study was to develop a frictional motion material with excellent corrosion and wear resistance in marine environments by generating surface modification layers obtained by frictional reforming techniques using various fine powders mixed with carrier particles. As one means to achieve this, we constructed a system that simultaneously measures the corrosion and wear resistance characteristics of various frictional-reforming materials in artificial seawater under fretting conditions. Frictional reforming was performed on 18Cr-8Ni austenitic stainless steel using hard fine powders of Ti, TiN, Cr, Cr2N, and Al2O3 mixed with Al2O3 carrier particles. The time variations of the frictional and corrosion resistance of these materials in a 3.5 % NaCl solution under fretting conditions were then evaluated simultaneously. The results showed that stainless steel modified by frictional reforming using a mixture of TiN powder and Al2O3 carrier particles has excellent corrosion resistance. However, its wear resistance may be inferior to that of stainless steel

Design guidelines of surface texturing to improve lubrication characteristics under reciprocating motion

The purpose of the present study is to clarify the effect of surface texturing on lubrication characteristics of a sliding surface under reciprocating motion and to develop design guidelines for surface texturing in order to obtain lower friction. To achieve this purpose, the lubrication characteristics of a sliding surface with dimple-shaped texturing during reciprocating motion are numerically analyzed by solving the Reynolds equation. The effects of texturing are compared with those of no texturing under various operating conditions as determined from the sliding speed, viscosity coefficient of the lubricant, and surface pressure, and the placement and dimensions of the texturing that result in lower friction are evaluated. The results show that in the oil film pressure distribution generated by the slider without texturing, friction loss is reduced by applying texturing at the location where the maximum value of this oil film pressure occurs. In this case, under the conditions analyzed in the present paper, the texturing reduces friction loss by 5 to 7%