| With the rapid development of manufacturing technology,the requirements of machining technology have been gradually raised,which is both an opportunity and a great challenge for the industry of cemented carbide coated cutting tools.Tool wear is the biggest problem that affects its service life.The tools that fail due to wear account for the vast majority of the failed tools every year.It is of great economic value to reduce the wear and improve the service life of the tools.The surface coating technology of cemented carbide tool can not only guarantee the strength and toughness of the tool,but also give it better wear resistance and oxidation resistance.In recent decades,TiAlN coating material has been widely used in carbide cutting tools due to its series of excellent properties.In addition,cryogenic treatment,as an extension of traditional heat treatment,plays a significant role in improving the wear resistance of cemented carbide tools.In this paper,TiAlN coating was prepared on YG10 square carbide milling cutter by multi-arc ion plating technology,and the influence of negative bias on TiAlN coating surface morphology,coating thickness,microhardness and film-base adhesion,as well as tribological properties in atmosphere and deionized water was analyzed by single factor variable method.On this basis,the influence of cryogenic time on TiAlN coating surface morphology,coating thickness,microhardness and membrane base adhesion,and tribological properties in atmospheric and deionized water environments were studied.Some findings are as follows:1.With the increase of the negative bias pressure,the hardness and binding force of the coating increased firstly and then decreased.When the negative pressure was-150 V,the hardness and binding force of the coating reached the highest,which were 2787.9 HV and64.7 N,respectively.In atmospheric and deionized water environments,the friction coefficient and volume wear rate of the coating decrease first and then increase with the increase of the negative bias pressure.The lowest friction coefficient in the deionized water environments is 0.6?-150 V?,and the lowest volume wear rate2.5?10-12 m3/N·m?-150 V?.The lowest friction coefficient In atmospheric environment is 0.48?-150 V?,and the lowest volume wear rate is1.8?10-12 m3/N·m?-150 V?.2.The oxidized coating is mainly composed of TiN,TiO2,AlN and Al2O3 phases.The thermal expansion coefficient of TiO2,Al2O3 and TiN and AlN are different from each other,which is easy to generate stress and cause the coating to crack easily.With the increase of the oxidation temperature,the micro-vickers hardness and binding force of TiAlN coating showed a decreasing rule.When the oxidation temperature was 800?,the hardness of TiAlN coating was the lowest 2196.09 HV,and the binding force was 60.00 N.With the increase of oxidation temperature,the width,depth and volume wear rate of the coating increase.When the oxidation temperature is 800?,the coating has the maximum width,depth and volume wear rate,which are 267.69?m,2.61?m and11.2?10-12 m3/N·m,respectively.The main wear mechanism of coating is abrasive wear.3.Cryogenic treatment had an important effect on the hardness and binding force of the coating.With the extension of cryogenic time,the hardness and binding force of TiAlN coating increased first and then decreased.When the cryogenic time was 36h,the maximum hardness value of the coating was 3611.1 HV and the binding force was 69.70 N.With the increase of cryogenic time,the diffraction peak intensity of AlN?111?crystal plane gradually increases,and the diffraction peak intensity is the largest when the cryogenic time is 36 h.The optimal orientation of AlN?111?crystal plane may be caused by the volume shrinkage of the coating and the stress transfer of the substrate under cryogenic conditions,resulting in new stresses on the coating,resulting in grain torsion and the optimal orientation along the AlN?111?crystal plane.With the extension of cryogenic cooling time,the friction coefficient and volume wear rate of TiAlN coating in deionized water environment and In the atmospheric environment tend to decrease first and then increase.in deionized water environment,when the cryogenic time is 36 h,the friction coefficient is 0.51 and the volume wear rate is 1.8?10-13 m3/N·m?36 h?,In the atmospheric environment,when the cryogenic cooling time is 36 h,the friction coefficient is 0.40 and the volume wear is 1.3?10-13 m3/N·m?36 h?. |
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