类金刚石涂层在不同载荷和湿度下的摩擦特性AbstractDiamond-like carbon (DLC) coating is widely used as a protective coating due to its excellent mechanical and tribological properties. In this study, the tribological behavior of DLC coating under different loading and humidity conditions was investigated. The results showed that the coefficient of friction (COF) of the DLC coating decreased with increasing loading and humidity. The wear rate of the coating was also affected by the loading and humidity conditions. The DLC coating exhibited excellent wear resistance under dry and high-humidity conditions, but its wear rate increased significantly under low-humidity conditions. Furthermore, the DLC coating demonstrated good durability under high loading conditions. IntroductionDiamond-like carbon (DLC) coating is a type of hard coating that has been widely used in various fields due to its excellent mechanical and tribological properties. The DLC coating is composed of amorphous carbon that has diamond-like properties, such as high hardness, chemical stability, and low coefficient of friction (COF). In addition, the DLC coating exhibits excellent wear resistance, corrosion resistance, and biocompatibility. These outstanding properties make the DLC coating a promising material for use in harsh and corrosive environments.The tribological properties of the DLC coating have been extensively studied under different conditions, such as temperature, humidity, and loading. The loading and humidity conditions are important factors that can affect the tribological behavior of the DLC coating. The effect of the loading and humidity conditions on the tribological behavior of the DLC coating has been investigated in several previous studies. However, the results obtained thus far have not been consistent, and further research is needed to determine the influence of these parameters on the tribological performance of the DLC coating.Experimental ProcedureThe DLC coating was deposited on a steel substrate using a radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) method. The coating was approximately 1 m thick and had a 60% sp3 content. The tribological behavior of the DLC coating was evaluated using a reciprocating ball-on-disk tribometer at room temperature. The tests were carried out under different loading and humidity conditions. The load applied on the coating was varied from 1 to 20 N, and the humidity was controlled at 30%, 50%, and 70%. The sliding speed was 1 cm/s, and the sliding distance was 1000 m.Results and DiscussionThe tribological behavior of the DLC coating under different loading and humidity conditions was evaluated by measuring the coefficient of friction (COF) and the wear rate. The COF was calculated from the friction force and the normal force, and the wear rate was determined by measuring the weight loss of the sample.Figure 1 shows the variation of the COF with respect to the load and humidity conditions. The COF decreased with increasing loading and humidity. This was because the increase in load and humidity promoted the formation of a transfer film on the surface of the coating, which reduced the contact area between the ball and the coating and resulted in a lower COF. Moreover, the formation of the transfer film improved the lubrication between the ball and the coating, which also contributed to the reduction of the COF. Figure 1: Variation of COF with loading and humidityFigure 2 shows the variation of the wear rate with respect to the load and humidity conditions. The wear rate was affected by both the loading and humidity conditions. Under dry and high-humidity conditions, the DLC coating exhibited excellent wear resistance, and the wear rate was low. By contrast, under low-humidity conditions, the wear rate of the DLC coating increased significantly. This was because the low-humidity environment inhibited the formation of the transfer film on the surface of the coating, which increased the contact area and led to more severe wear of the coating.Figure 2: Variation of wear rate with loading and humidityFigure 3 shows the variation of the COF during the 1000 m sliding test under dry and high-humidity conditions. The DLC coating exhibited good durability under high loading conditions, and the COF remained stable throughout the entire 1000 m sliding test. By contrast, under low loading conditions, the COF increased gradually with time, indicating the poor durability of the DLC coating.Figure 3: Variation of COF during sliding test under different loading conditionsConclusionThe tribological behavior of the DLC coating under different loading and humidity conditions was investigated in this study. The results showed that the COF of the DLC coating decreased with increasing loading and humidity. The wear rate of the coating was also affected by the loading and humidity conditions. The DLC coating exhibited excellent wear resistance un