論文
アルミニウム合金へ成膜したSi-DLC/DLC多層膜の膜特性におよぼす積層回数および膜厚比の影響
2019 年 83 巻 3 号 p. 82-86
詳細
2019 年 83 巻 3 号 p. 82-86
Aluminum alloys are light and have good workability; however, their low hardness and poor wear resistance are drawbacks limiting their wide application in the automotive industry. The deposition of diamond-like carbon (DLC) films, which exhibit high hardness and good wear resistance, onto the surface of Al alloy substrates, can overcome these drawbacks. As Al alloys and DLC films have low affinity for each other, adhesion between the two is poor; adhesion can be improved by using of an interlayer. For coatings with the same thickness, film properties are improved by forming multilayer structures. In this study, the sample was formed with a uniform film thickness of 2 µm, to change the thickness ratio of the Si-DLC/DLC layer to 1:1 or 1:3 and to change the number of multilayers [Si-DLC/DLC]N to 1, 2, and 4. The samples were then tested by nanoindentation, Rockwell indentation, scratch, and wear tests. The sample with a thickness ratio of 1:1 increased the hardness and hardness/Young's modulus (H/E) of the film by increasing the number of multilayers repetitions. However, for the sample with a thickness ratio of 1:3, 2 and 4 multilayer repetitions did not effect a significant difference in the hardness and H/E ratio. These samples did not improve the adhesion properties, because of no significant difference by the Rockwell indentation and scratch tests. By the wear test, samples with a 1:1 thickness ratio of the multilayer increased the delamination length and decreased the friction coefficient with increasing number of multilayers repetitions. Samples with a 1:3 thickness ratio of the multilayer increased the delamination length with increasing number of multilayers repetitions, whereas samples with 2 and 4 multilayers did not cause a significant difference in the delamination length. Moreover, the friction coefficient of the samples decreased with increasing number of multilayers repetitions. This study showed the delamination length of DLC films is proportional to increasing H/E ratio.
