TiB2涂层刀具制备及干铣削Ti-6Al-4V磨损行为研究?

Preparation of TiB2 Coated Tool and Wear Behavior of Dry Milling Ti-6Al-4V

由于切削过程中产生高温、刀具粘结与氧化严重,钛合金切削尤其是干切削,一直是刀具行业的重大挑战之一,而在刀具表面添加涂层是提高钛合金切削刀具寿命的有效途径。利用脉冲磁控溅射技术制备了TiB2涂层刀具,以相同基体的无涂层刀具为对照,干铣削Ti-6Al-4V钛合金,切削速度从30~100 m/min变化,研究TiB2涂层刀具的切削性能与失效机理。所制备的TiB2涂层具有(100)择优取向的六方晶体结构,组织致密。涂层硬度可高达4000 HV。切削实验发现,在30 m/min的低速时,TiB2涂层刀具的切削寿命超过无涂层刀具57%之多,当切削速度加倍到60 m/min时,刀具寿命未见下降。当切削速度增加到100 m/min时,TiB2涂层刀具与无涂层刀具切削寿命相当。TiB2涂层刀具表面氧化所产生的B2O3液化膜,起自润滑作用,可充分减少钛合金的粘结,降低摩擦力。因此,在TiB2或B2O3消失之前,TiB2涂层刀具均有良好表现。在100 m/min时,切削高温造成B2O3强烈挥发,且TiB2被氧化为多孔疏松的TiO2,刀具寿命急剧下降到无涂层刀具的水平。

Due to the high temperature, adhesion and oxidation generated during machining, machining of titanium alloys, especially dry cutting, has always been one of the major challenges in the tool industry. It is an effective way of coating on the tool surface to improve the tool life of titanium alloy cutting tool.TiB2 coated tools were prepared by pulsed magnetron sputtering. Then compared with the uncoated tools with the same substrate, TiB2 coated tools were used to dry mill Ti-6Al-4V titanium alloy. The cutting speed was changed from 30 m/min to 100 m/min, and the cutting performanceand failure mechanism of TiB2 coated tool was studied. The TiB2 coating exhibited(100) preferentially oriented hexagonal crystal structure with good crystallinity and compactness. The vickers hardness of coating is up to 4000 HV. The tool life of Ti B2 coated tools exceeded 57% of uncoated tools at low speed of 30 m/min in the cutting experiment. When the cutting speed doubled to 60 m/min, the tool life did not decrease. When the cutting speed is increased to 100 m/min, the TiB2 coated tool has the same cutting life as the uncoated tool. The B2O3 liquefied film produced by the surface oxidation of the TiB2 acts as a self-lubricating agent, which can sufficiently reduce the adhesion of the titanium alloy and reduce the friction. Therefore, TiB2 coated tools have performed well before TiB2 or B2O3 disappeared. At 100 m/min, the high temperature generated in the machining caused B2O3 to volatilize strongly, while TiB2 was oxidized to porous and loose TiO2, and the tool life dropped sharply to the level of uncoated tools.