【摘要】 目的 基于配置直流脉冲偏压电源的多功能镀膜系统，探究钢管内表面DLC薄膜制备工艺。方法 采用等离子体化学气相沉积技术，以甲烷与氩气为前驱气体，通过调节甲烷流量、偏压、占空比在304不锈钢管内表面制备DLC薄膜。利用SEM、AFM、Raman和FTIR对薄膜的微观形貌与结构进行表征；采用SEM与三维表面轮廓仪分别对Si基底与304不锈钢基底上的薄膜厚度进行测量；通过洛氏硬度计、残余应力测试仪和纳米压痕仪对薄膜结合力、残余应力以及力学性能进行评价。利用正交试验设计与方差分析，对甲烷流量、偏压和占空比进行影响程度分析；利用加权和模型进行多目标优化分析，得出管道内壁DLC薄膜最佳制备工艺。结果 占空比对管道内壁温度、平均功率、薄膜结合力、残余应力、硬度、弹性模量及成膜面积影响最大，甲烷流量对沉积速率影响最大，偏压对表面粗糙度影响最大。最佳制备工艺为甲烷流量10 cm~3/min、偏压500 V、占空比5%，该工艺下沉积速率为7.8 nm/min、表面粗糙度为0.43 nm、成膜面积达88.18%、结合力等级为HF3、纳米硬度与弹性模量分别为16.256 GPa和135.668 GPa。结论 通过正交试验结合方差分析与加权和模型可快速确定因素影响程度以及目标工艺参数。占空比主要通过影响偏压电源平均功率来调控内壁温度，从而影响DLC薄膜的结构与性能。更多还原

【Abstract】 Metal pipes are widely used in mechanical, chemical, and energy industries. However, under harsh service conditions, their inner surfaces are prone to wear, corrosion, and oxidation, often resulting in premature failure. Among various inner-surface strengthening techniques, plasma-enhanced chemical vapor deposition(PECVD) demonstrates distinct advantages in forming uniform coatings on the inner walls of elongated or curved metal pipes. Depositing diamond-like carbon(DLC) films on the inner surfaces using PECVD, due to their high hardness, excellent wear resistance, and chemical stability, is considered an ideal method for surface reinforcement. In recent years, most studies focused on the effects of single process parameters on PECVD deposition behavior, while systematic investigations of multiple parameters and their interactions remained limited. Orthogonal experimental design provides an effective approach for analyzing the significance of multiple factors and optimizing the deposition process efficiently. In this study, a multifunctional coating system equipped with a pulsed direct-current bias power supply is employed to deposit DLC films on the inner walls of 304 stainless steel pipes with an inner diameter of 40 mm, wall thickness of 2.5 mm, and length of 420 mm, with methane and argon as precursor gases. The microstructure and morphology of the films are characterized by scanning electron microscopy(SEM), atomic force microscopy(AFM), Raman spectroscopy, and Fourier transform infrared spectroscopy(FTIR). Film thickness is measured with a profilometer, while adhesion strength, residual stress, and mechanical properties are evaluated with a Rockwell hardness tester, a residual stress analyzer, and a nano indenter, respectively. Variance analysis is conducted to determine the effects of three major process parameters, methane flow rate, bias voltage, and duty cycle, on six indices: deposition rate, surface roughness, deposition area, adhesion area, hardness, and elastic modulus. A weighted-sum model is applied to perform multi-objective optimization of the deposition process. The results show that duty cycle has the most significant influence on inner-wall temperature, average power, adhesion strength, hardness, elastic modulus, deposition area and thickness uniformity, followed by bias voltage and then methane flow rate. For residual stress, duty cycle has the greatest effect, followed by methane flow rate and bias voltage. Deposition rate is primarily affected by methane flow rate, followed by duty cycle and bias voltage. Surface roughness is most strongly influenced by bias voltage, followed by methane flow rate and duty cycle. Multi-objective optimization identifies the optimal process parameters as a methane flow rate of 10 cm~3/min bias voltage of 500 V, and duty cycle of 5%. Under these conditions, the deposited DLC films exhibit a deposition rate of 7.8 nm/min, surface roughness of 0.43 nm, deposition area of 88.18%, adhesion grade of HF3, and a nano-hardness and elastic modulus of 16.256 GPa and 135.668 GPa, respectively. This study systematically reveals the influence of methane flow rate, bias voltage, and duty cycle on the deposition behavior, microstructural characteristics, and mechanical properties of DLC films deposited on the inner walls of pipes via PECVD. By integrating variance analysis with multi-objective optimization, the study provides a rapid and systematic method for identifying critical process parameters that govern film performance. The findings offer theoretical support and practical guidance for the optimization of PECVD processes for inner-surface pipe applications, contributing to the development of high-performance, durable DLC coatings for metal pipes operating under severe service conditions. In summary, this study systematically reveals the effects of PECVD process parameters on the deposition behavior and overall performance of DLC films on the inner walls of pipes. It establishes a process screening method that combines variance analysis with multi-objective optimization, providing an important theoretical basis and technical guidance for the rapid optimization and controllable deposition of DLC coatings on inner surfaces of pipes.更多还原