Protective coatings with a heterophase layered structure were obtained by reactive electrospark treatment (EST) of niobium substrate with a fusible AlCaSiY electrode. The effect of the frequency–energy modes of EST on the phase composition, structure and properties of the coatings was studied. A combination of high discharge current values (400A) and long pulses (100 μs) yields a double-layer coating with the total thickness of 80 μm, which consists of the (Al) matrix strengthened with NbCaAl particles and a hard (10 GPa) NbAl layer. The results of pin-on-plate tribological testing revealed that this structure made it possible to reduce the coefficient of friction from 0.42 to 0.24 and increase wear resistance 3.5-fold compared to those of niobium. Oxidative annealing of Nb plates in air at 700 °C causes their fracture due to the formation of NbO. Indeed, oxidative annealing of the samples subjected to EST leads to formation of a dense CaAlSiO-oxide based near surface layer that inhibits oxygen diffusion into the bulk, thus suppressing NbO formation. Mass gain of the sample having a protective coating after 300-min isothermal exposure was 2.54 mg/cm, which is 3.6-fold lower than that for the Nb substrate (9.04 mg/cm).

中文翻译：

---

使用易熔AlCaSiY电极通过反应电火花处理提高铌基体的耐磨性和耐热性


通过使用易熔 AlCaSiY 电极对铌基体进行反应电火花处理 (EST)，获得了具有异相层状结构的保护涂层。研究了EST的频率-能量模式对涂层的物相组成、结构和性能的影响。高放电电流值 (400A) 和长脉冲 (100 μs) 的组合产生了总厚度为 80 μm 的双层涂层，该涂层由 NbCaAl 颗粒强化的 (Al) 基体和硬质 (10 GPa) 组成NbAl层。销板摩擦学测试结果表明，与铌相比，这种结构可以将摩擦系数从 0.42 降低到 0.24，耐磨性提高 3.5 倍。铌板在空气中于 700 °C 下进行氧化退火会因形成 NbO 而导致其断裂。事实上，经过 EST 处理的样品的氧化退火会导致在近表面层形成致密的 CaAlSiO-氧化物，从而抑制氧扩散到本体中，从而抑制 NbO 的形成。等温暴露 300 分钟后，具有保护涂层的样品的质量增益为 2.54 mg/cm，比 Nb 基材 (9.04 mg/cm) 低 3.6 倍。