Search Results

Anodizing is applied to improve the durability and the corrosion resistance of aluminum alloy parts of engines and car bodies. Generally, anodic oxide film is formed using direct current anodizing (DCA). However, in the case of anodizing high silicon aluminum alloy cast parts, it is difficult to derive uniform film thickness distribution. Furthermore, it takes a long treatment time which causes low productivity. In this study, the authors have developed an anodizing method by using high-frequency switching anodizing (HSA) to solve these problems. The growth process of anodic oxide film is susceptible to the metallographic structure. Thus, the typical DCA application to the high silicon aluminum alloy produces a non-uniform film thickness, while HSA has the potential to form uniform film without being affected by metallographic structure. Moreover, the current density of HSA is higher than that of DCA which reduces treatment time to 1/5 as the film formation enhances.

The development of a long life rolling element bearing for use under severe conditions is fundamental and important technology from an economic and environmental standpoint. Previously, NTJ2 was developed as a semi-heat resistant long life bearing steel, using silicon as an alloying element to enhance its heat resistance and life. It is thought, though, that the demand for a bearing material that can withstand higher temperatures and have a longer life than NTJ2 will be needed in the future. Thus, a new heat resistant, long life material called STJ2 was developed optimizing the alloying elements in the silicon-alloyed bearing steel. The new steel has good dimensional stability to 250°C, long life and is very resistant to surface damage.