Structural Control of Surface Modified Layrs through Ultrasonically Distributed Electrical Discharges.

为了改善铝基复合材料的摩擦磨损性能，采用超声振动强制分散放电的方法对铝基复合材料进行了表面改性。包含在绿色致密电极中的钛以及从工作流体分解的碳和硅通过单个放电电弧转移到基底表面。由于超声振动对铝合金基体的作用，使铝合金基体中元素的转移量增加，改性层的厚度显著增加。然后，原位TiC在改性表面中的体积分数增加施加超声振动，从而改性表面的硬度变高。放电合金化的过程不仅可以在几分钟内涂覆含有原位TiC的复合层，其厚度接近80 μ m，而且可以通过施加超声振动获得高体积分数的TiC，超声振动是放电条件的附加工艺参数。通过改变TiC的体积分数，可以将改性表面的硬度控制在4-14 GPa的范围内，并提高了改性表面的耐磨性。

In order to improve friction and wear characteristics, surface modification of aluminum matrix composites was carried out by applying the new method named Electrical Discharge Alloying, in which each electrical discharge is forcibly scattered by ultrasonic vibration. Titanium contained in the green compact eletrode, and also carbon and silicon decomposed from the working fluid are transferred to the substrate surface through a single discharged arc. Sinece the application of ultrasonic vibration to the aluminum alloy substrate makes the amount of transferred elements increase, the thickness of modified layrs remarkably become thicker. Then, the volume fraction of in situ TiC in the modified surface increases with applying ultrasonic vibration, so that the hardness of modified surfaces becomes high. The process, electrical discharge alloying, makes it possible not only to coat a composite layr containing in situ TiC with a thickness of nearly 80 mum within a few minutes, but also to get high volume fractions of TiC by applying ultrasonic vibration, which is an additional process parameter to discharge conditions. Hradness of the modified surfaces can be controlled to have any value of 4-14 GPa by varying the volume fraction of TiC.It is also recognized that the process improves wear resistance of the modified surfaces.