化学气相沉积温度对AZ31镁合金表面制备DLC薄膜微观结构及机械性能的影响

目的提高镁合金表面硬度及耐磨性,给出最佳性能薄膜的制备温度。方法采用化学气相沉积(PECVD)技术在AZ31镁合金表面制备了含氢DLC薄膜,研究了沉积温度对DLC薄膜厚度、表面形貌、硬度、杨氏模量、耐磨性能、膜基结合力以及sp^3键含量的影响,并对相应的影响机制进行了讨论。结果沉积温度对AZ31镁合金表面DLC膜的组织及性能有显著影响。温度较低时,碳粒子能量较低,无法注入薄膜亚表层,只能停留在表面以sp^2杂化方式生长。随着温度的升高,碳粒子能量增加,更多的sp^3杂化键形成。沉积温度为75℃时,薄膜中sp^3杂化键含量最多,此时薄膜最厚约为7.67μm,硬度最大可达5.95 GPa,杨氏模量值最高达到43.2 GPa,并且摩擦系数最低仅为0.03。随着温度进一步升高,碳粒子能量持续增加,轰击薄膜表面时会使碳-氢键断裂,造成氢的脱附,使薄膜中sp^3杂化键减少,从而降低了薄膜的硬度及耐磨性等机械性能。结论在本研究工作温度范围内,75℃为AZ31镁合金表面制备DLC薄膜的最佳温度。

Effect of Temperature on Microstructures and Mechanical Properties of DLC Films Prepared on AZ31 Magnesium Alloy by Chemical Vapor Deposition

The work aims to enhance the surface hardness and wear resistance of magnesium alloy.Provide the optimal preparation temperature of excellent properties of the film.A hydrogen-containing DLC film was prepared on the surface of AZ31 magnesium alloy by plasma-enhanced chemical vapor deposition(PECVD)technology.The effects of deposition temperatures on the thickness,surface morphologies,hardness,Young’s modulus,wear resistance,bonding force and the contents of sp^3 bond were studied.The corresponding mechanism of the influence of temperature was also discussed.The results show that the deposition temperatures have significant effect on the microstructures and properties of the DLC film on the surface of AZ31 magnesium alloy.At lower temperatures,the energy of carbon particles were lower.Therefore,the carbon particles cannot be injected into the subsurface of the film.They can only stay on the surface and growth by the form of sp^2 hybrid.With the increase of temperature,the energy of carbon particles were increased and more sp^3 hybrid bonds were formed.The hybrid forms of DLC film are mainly sp^3 bonds at the deposition temperature is 75℃.At this temperature,the value of film thickness is about 7.67μm,the value of film hardness is 5.95 GPa,the value of film Young’s modulus is 43.2 GPa and the value of film friction coefficient is only 0.03.As the further increase of temperature,the energy of the carbon particles are increased continually.Therefore,the carbon-hydrogen bonds are broken under the bombardment of high energy carbon particles.The bombardment can result in the desorption of hydrogen,which can reduce the content of sp^3 hybrid bond in the film.Therefore,the mechanical properties such as hardness and wear resistance are decreased.In this study,the optimum temperature for the preparation of DLC film on the surface of AZ31 magnesium alloy is 75℃.