Anodicoxidation treatment, when applied to aluminum and its alloys, can increase the surface hardness and resistance to abrasive wear. Furthermore, it can form surface self-lubricating composites when adding some appropriate lubricants to those pores of anodized film such as MoS2 or PTFE. Various methods have been studied in order to improve friction performance of aluminum anodic oxide coating, such as physical impregnation, duplex anodization, sputter-deposition, electrophoretic-deposition and Teflon technology, etc. The methods of physical impregnation and electrophoretic deposition have been used widely for their convenient and economic character. However, their filling efficients are both low since the pores of anodized film on aluminum are nano-size. Duplex anodization is the method to deposit solid lubricant, such as MoS2, in the pores of anodized film on aluminum by reanodizing in (NH4)2MoS4 solution. Some researchers think the deposited products were sulphides of Mo rather than single MoS2, which decrease the self-lubricating properties of the materials. Sputter-deposition films of MoS2 have been used as lubricants for space applications. Since its high cost, its applications in normal industry, especial civil industry, are not available. Teflon technologymay lead to the distortion of the samples because it uses the force of press, and it also restricted by the shape of the samples and cannot be available in complex samples and small samples. In order to wide the application of the solid lubricating films in the industry, a cheaper, more convenient and widely used method is desired. A self-lubricating anodic film has been formed on aluminum by anodization in phosphoric acid–base electrolyte and a subsequent technique containing ultrasonic impregnation and heat treatment. The results show that the ultrasonic impregnation after anodization of aluminum in an electrolyte of phosphoric acid and some additives can fill some PTFE into the holes of alumina and the surface hardness decreases little within appropriate ultrasonic time. The final heat treatment technology can increase the coating hardness greatly, especially to the alumina acquired by general anodization. With this fabricating method, the properties of anti-attrition and abrasion resistance of self-lubricating coating improved greatly.
本文由桑尧热喷涂网收集整理。本站文章未经允许不得转载；如欲转载请注明出处，北京桑尧科技开发有限公司网址：http://www.sunspraying.com/
|
