Abstract To improve the traditional laser cladding self-lubricating coating technique, a new type of self-lubricating composite coating is proposed in this study. This novel structural-coupling self-lubricating wear-resistant coating (SSWC) is fabricated on stainless steel using a laser cladding + vacuum pressure thermal-diffusion welding (VPTW) process. The coating has an interlaced-stripe structure from an organic combination of separated wear-resistant units (WUs) and self-lubricating units (SUs), which are prepared using NiCrSiB powder and Cu-coated graphite composite powder, respectively. The WUs have a microstructure consisting of a Ni-rich γ- (Ni, Fe) matrix and Cr-rich carbide and boride precipitates, and the SUs primarily consist of Cu matrix and graphite. Distinctive microstructures determine the obvious increase in the hardness of the WUs compared to the substrate and the decrease in the hardness of the SUs. As a result, microhardness with alternating softness and hardness occurs on the surface of the SSWC. The tribological properties of the SSWC are evaluated through the reciprocating friction and wear test compared with the as-received substrate, NiCrSiB coating and Cu-G coating at room temperature. The results exhibit considerably better antifriction properties of the SSWC compared to other wear specimens. This property can be attributed to the positive role of the SUs contained in the SSWC, which have a self-lubricating property and promote the formation of tribofilm with a lubricity and protection on the worn surface of WUs by sliding action. The wear mechanism of SUs is mainly abrasive wear. In contrast, the main wear mechanism of WUs varies with the sliding time: abrasive wear at the initial stage that shifts to delamination wear and abrasive wear after long-term sliding due to the generation of tribofilm. Additionally, a synergistic relationship between the WUs and SUs was observed during the wear process, which can lead to the specific tribological properties of the SSWC.

中文翻译：

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基于结构耦合的自润滑耐磨涂层的制备及摩擦学性能

摘要 为了改进传统的激光熔覆自润滑涂层技术，本研究提出了一种新型的自润滑复合涂层。这种新型结构耦合自润滑耐磨涂层 (SSWC) 是使用激光熔覆 + 真空压力热扩散焊接 (VPTW) 工艺在不锈钢上制造的。该涂层具有由分离的耐磨单元 (WU) 和自润滑单元 (SU) 有机组合而成的交错条纹结构，它们分别使用 NiCrSiB 粉末和 Cu 包覆石墨复合粉末制备。WUs 的微观结构由富含 Ni 的 γ-(Ni, Fe) 基体和富含 Cr 的碳化物和硼化物沉淀组成，SUs 主要由 Cu 基体和石墨组成。独特的微观结构决定了与基材相比，WU 的硬度明显增加，而 SU 的硬度降低。结果，SSWC 表面出现软硬交替的显微硬度。SSWC 的摩擦学性能通过往复摩擦和磨损试验与原样的基材、NiCrSiB 涂层和 Cu-G 涂层在室温下进行比较来评估。结果表明，与其他磨损试样相比，SSWC 的减摩性能要好得多。这种特性可归因于包含在 SSWC 中的 SU 的积极作用，其具有自润滑特性，并通过滑动作用促进在 WU 的磨损表面上形成具有润滑和保护作用的摩擦膜。SUs的磨损机制主要是磨粒磨损。相比之下，WUs的主要磨损机制随着滑动时间的变化而变化：初始阶段的磨粒磨损，由于摩擦膜的产生，在长期滑动后转变为分层磨损和磨粒磨损。此外，在磨损过程中观察到 WU 和 SU 之间的协同关系，这可能导致 SSWC 的特定摩擦学特性。