气体流量对LPCVD ZrC涂层结构和沉积机理的影响

Effect of Total Flow Rate on Morphology and Growth Mechanism of ZrC Coating Prepared by LPCVD

摘要:

摘要：利用低压化学气相沉积工艺，采用Zr-Br2-C3H6-H2-Ar反应体系，在石墨基底表面制备了ZrC涂层。研究了气体流量对ZrC涂层微观形貌和沉积机理的影响。随着气体流量由200 ml/min向1000 ml/min增大，涂层的沉积速率先增大后减小，极大值为3.37 g-3?cm-2?h-1。同时，涂层的择优取向发生了明显的变化，在600~800 ml/min范围内时，涂层具有稳定且强烈的(200)晶面择优取向。XPS分析结果表明，沉积产物中的C/Zr比也随气体流量的增大，相应的由0.85快速的升高到1.49。当气体流量为200 ml/min时，涂层致密光滑，ZrC晶粒具有典型的等轴晶结构特征；当气体流量为400~800 ml/min时，涂层光滑平坦，ZrC晶粒具有规则的四面体结构；当气体流量为1000 ml/min时，涂层表面存在着大量不规则的岛状、弓状颗粒。基底表面边界层厚度的变化是影响涂层沉积过程的主要因素。

Abstract:

Abstract: Zirconium carbide (ZrC) coatings were deposited on graphite substrate at 1200°C by low pressure chemical vapor deposition (LPCVD) from the Zr-Br2-C3H6-H2-Ar system. The effect of total flow rate on the morphology and growth mechanism of ZrC coatings were investigated. As the total pressure increased, the deposition rate increased firstly and then decreased slowly, the maximum value was 3.37 g-3?cm-2?h-1. Meanwhile, the preferential orientation of ZrC coatings changed evidently, the (200) plane was the preferential orientation of ZrC coatings at the total flow rate of 600~800 ml/min. XPS showed that the C/Zr ratio of ZrC coatings increased from 0.85 to 1.49. At the total flow rate below 200 ml/min, the ZrC coatings were dense and composed of equiaxed gain structure. As the total flow rate increased from 400 to 800 ml/min, the ZrC coatings were well-faceted pyramidal-shaped crystals. When the total flow rate above 1000 ml/min, the ZrC coatings with a loose complex island-like gains. The variations of ZrC coatings can mainly be attributed to boundary layer with increasing the total flow rate.