X射线测量高速钢上不同厚度氮化钛涂层残余应力

采用多弧离子镀在AISIM2高速钢(HSS)上沉积了TiN硬涂层,试样中基体厚度为1mm,涂层厚度分别为3.0、5.0、7.0、9.0和11.0μm.应用X射线衍射(XRD)分析了TiN涂层中残余应力,测量了TiN(220)衍射晶面在五种不同倾斜角(Ψ=0°,20.7°,30°,37.8°和45°)下的X射线衍射峰.结果表明:在3～11μm涂层厚度范围内,TiN涂层中均表现出残余压应力且残余压应力值较大.TiN涂层中残余应力大致分布在-3.22～-2.04GPa之间,本征应力分布在-1.32～-0.14GPa,热应力约为-1.86～-1.75GPa.TiN涂层中残余应力值随涂层厚度变化是非线性增加的,随厚度增加表现出先增大后减小的变化趋势,多项式拟合后发现约在8.5μm厚时残余应力达到最大值.

X-ray residual stress analysis in different thickness TiN coatings on high-speed-steel substrates

Multi-arc ion plating technique has been used to deposite hard TiN coatings on AISI M2 high speed-steel(HSS) substrates.The thickness of the substrate was 1.0 mm in all the samples,while five thicknesses of the TiN coatings,respectively,3.0,5.0,7.0,9.0 and 11.0 μm were used.X-ray diffraction(XRD) has been used for measuring residual stress on TiN coatings.The stresses along five different directions(Ψ =0°,20.7°,30°,37.8° and 45°) on the coating surface have been measured by recording the peak positions of TiN(220) reflection for each 2θ at different tilt angles Ψ.Regardless of the thickness change of TiN coatings employed on substrate,residual compressive stresses are present in the TiN layers.Furthermore,the results reveal the residual stresses in the TiN layers are high.While the coatings thickness changed from 3μm to 11μm,the residual stresses in the TiN coatings varied from-3.22 to-2.04GPa,the intrinsic stresses varied from-1.32 to-0.14GPa,the thermal stresses varied from-1.86 to-1.75GPa.The residual stresses in TiN coatings shew a nonlinear change with the increasing coatings thickness.When the coatings thickness was about 8.5μm,the residual stresses in TiN coatings reached to the maximum by fitting polynomial.These changes ascribes to the defects in the TiN coatings,such as the micro-holes,cooling liquid drops and micro-cracks near the interface between the coating and the substrate,increase with the increasing TiN coatings thickness,which leads the residual stresses in TiN coatings to release effectively.