Study On The Coating Of Tools And Its Performance Of High Speed Milling Aluminum Alloy

In recent years, under the pressure of tooling cost and efficiency, high speed machining of aluminum alloy has become the main development direction.Thus, aluminum alloy machining tool requirements are getting higher and higher. In view of the current processing problems of aluminum alloy, a new kind of Cr N/Cr-Si-N/ C coating were prepared by Hollow cathode + multi arc ion plating equipment in my present work. Scanning electron microscopy(SEM); Rockwell apparatus; CSM Nanoindentor, X-ray diffraction; Raman spectroscopy were used to characterize the microstructure and properties. SFT-2M pin on disk wear testing machine were used to characterize wear behavior of coating and aluminum alloy. Composite coated milling cutter were used to cutting aluminum alloy to characterizing the actual cutting properties of the coating, the results shows that:1. The surface of Cr, Cr N, Ti N, Cr/Cr N four kinds of transition coating was prepared by the hollow cathode ion plating method are smooth, There are no large particles or droplets.Among these coatings, Cr coating has the highest crack propagation resistance which was improved by 44.7%, 37.8% and 29.7% compared with the Cr N, Ti N and Cr/Cr N coatings,the Cr N coating has the highest plastic deformation resistance which was improved341.7%、29.3% and 23.3% compared with the Cr N, Ti N and Cr/Cr N coatings compared with the Cr, Ti N and Cr/Cr N coatings. After consideration, Cr N coating were chosen to be the transition coating to improve the bonding strength between the coating and hard alloy substrate2. This paper uses Cr Si and Cr target preparation of Cr-Si-N coating and uneven distribution of Si, most of it were gathered in the different size of the drop. About 8-10% Si element added to improve the mechanical properties of Cr-Si-N coating: the largest hardness can reach 3000 HV0.01, bonding force can reach to 15 N, and compared Cr N coating, increased by 42.9%, 14.8%; At the same time, when the Si content is less than 10%, the surface of large particles and less aluminum adhesion will reduce the coefficient of friction of Cr-Si-N coating wear with ADC12 aluminum, lowest approximately 0.20.3. Used the hollow cathode electron gun as the ion source optimized carbon-based coating preparation process on the Cr N / Cr-Si-N coatings. When the bias reachs 650 V, vacuum chamber pressure at 0.5Pa and C2H2 / Ar gas ratio at 4, it will prepare a complete, compact, stable carbon-based coating on the Cr N / Cr-Si-N coatings.4. Raman spectroscopy reveals that carbon-based coating of the present paper prepared have high sp2 content, coating structure most were consist by graphite phase. Bias have a deep influence to the mechanical properties and the carbon-carbon bond form, when the bias reachs to 650 V coating have a good performance of mechanical properties; With increasing of bias, carbon-based coatings disorder increases, graphitization decreases.5. Wear of Cr N / Cr-Si-N / C composite coating with aluminum ADC12 showed that, with the load and wear time increases, the weight of aluminum transferred to the surface of the coating also increases. But a part of these transfers are the loose particles of aluminum;when the carbon-based coating complete compact, the adherent aluminum particles easily cleaned; only when after the local carbon-based coating peeling off, the aluminum particles will be adhered to and the sample and form a strong bond.6. Due to lubricating, low friction performance of Cr N / Cr-Si-N / C composite coated tool, it can significantly decrease aluminum bond and the formation of BUE when milling aluminum alloy, reduce tool wear and improve the ability of the cutter chip; tools life increased approximately 33% when compared to uncoated tool.