Study the effect of nitrogen content on the friction and wear properties of Zr-Cu-Ni-Al bulk metallic glasses

The effects of nitrogen on friction and wear properties of Zr-based bulk metallic glasses were investigated experimentally. Preparation of Amorphous Bars by copper mold suction casting method. XRD was used to characterize the structure of samples, which proved their amorphous structure. The surface properties of the samples were studied with a microhardness tester and a friction and wear tester. The wear surfaces of the sample were analyzed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The results show that the introduction of nitrogen improves the hardness and wear resistance of Zr-based metallic glass. Compared with the non-N-doped Zr-based metallic glass, the N-doped Zr-based metallic glasses have higher hardness and lower wear rate. In particular, the sample with 1.5% nitrogen doping has the largest hardness (578.58hv) and the lowest wear rate (1.04 × 10−3mm3 N−1 m−1). The wear types of N-doped Zr-based amorphous on GCr15 are mainly abrasive wear and adhesive wear.

Investigation on tribological behaviors of biodegradable pure Zn and Zn-X (Li, Cu, Ge) binary alloys

As a potential biodegradable implant material, zinc (Zn) alloys have attracted increasing attention due to their good biocompatibility and moderate degradation rate. Zn and its alloys are expected to become candidate materials for medical devices. The metals implanted in the human body will inevitably undergo friction in the human body before it is completely degraded. Friction and wear are essential factors which may cause medical devices’ service failure. However, there are still few studies on the friction and wear properties of biodegradable Zn-based alloys in the human body, and most studies just focus on the mechanical properties, degradation properties and biocompatibility of the alloys. Thus, it is crucial to study the friction and wear properties of Zn and its alloys. In the present work, we investigated the tribological properties of biodegradable pure Zn and Zn-X (Li, Cu, Ge) alloys. Our study found that under simulated body fluid and dry friction conditions, the addition of alloying elements Li and Cu can improve the friction properties of Zn. Among the four metals, Zn-0.5Li alloy has the lowest friction coefficient and the best wear resistance. Hank’s solution has lubricating and corrosive effects. That is to say, when the alloy is rubbed in Hank’s solution, it can not only be protected by the lubrication of the solution, but also tribocorrosion will occur as well.

Self-Lubricating Materials for Extreme Condition Applications

Lubrication for extreme conditions, such as high temperature, cryogenic temperature, vacuum pressure, high load, high speed, and corrosive environments, is a continuing challenge among tribologists and space engineers due to the inadequate friction and wear properties of liquid lubricants. As a result, tremendous research effort has been put forward to study lubrication mechanisms for various machine elements under challenging conditions over the past two decades. Self-lubricating materials have been most widely used for adequate lubrication in extreme conditions in recent years. This review paper presents state-of-the-art of materials for lubrication in extreme condition applications in aerospace, automotive, and power generation areas. More specifically, solid lubricants dispersed in various matrices for lubrication application were analyzed in-depth under challenging conditions. This study also reports the self-lubricating materials and their lubrication mechanisms. Finally, various applications and challenges of self-lubricating materials were explored.