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在精心控制的Ar-N_2气氛中沉积钼时,得到了溶解氮为0～10％(at)的均一体心立方相。厚度为10～20μm之镀层的X-射线图呈现很窄的谱线,并且具有平行于样品表面的(110)面的准理想取向。虽然这些镀层的努氏硬度为HK300～3000,但却仍然保持着相当良好的韧性和很低的摩擦系数,以及明显的“跑合”趋势,其摩擦系数由起始值0.1(机油润滑)很快就降低到0.07以下。当氮气分压高于0.1Pa时就出现氮化物相,同时镀层变脆且其X-射线衍射线变宽。与氧化钼的生成能(对于MoO_2,△H=-130cal/mol)相比,氮化钼的生成能(对于MoO_2N,△H=-8kcal/mol)很低,因而可以很好地控制氮含量。为了避免生成含有不稳定的面心立方相镀层,理想的温度应高于200℃。钨的行为与此十分相似,而铬尽管也能在同一体系中结晶,但却是以(100)面平行于样品表面,故其摩擦系数明显较高。
When molybdenum is deposited in a carefully controlled Ar-N 2 atmosphere, a homogeneous body-centered cubic phase with dissolved nitrogen of 0 to 10% (at) is obtained. The X-ray pattern of the coating with a thickness of 10-20 μm exhibits a very narrow spectral line and has a quasi-ideal orientation parallel to the (110) plane of the sample surface. Although the Knoop hardness of these coatings is HK300 ~ 3000, they still maintain a fairly good toughness and a very low coefficient of friction, as well as a clear “running-in” tendency with a friction coefficient of 0.1 (oil-lubricated) Fast down to 0.07 below. When the partial pressure of nitrogen is higher than 0.1 Pa, the nitride phase appears, and the coating becomes brittle and its X-ray diffraction line becomes wider. The formation energy of molybdenum nitride (ΔH = -8 kcal / mol for MoO 2 N) is very low compared with that of molybdenum oxide (ΔH = -130 cal / mol for MoO 2), so that the nitrogen content can be well controlled . In order to avoid the generation of unstable face-centered cubic coatings, the ideal temperature should be above 200 ° C. The behavior of tungsten is very similar to this, and although chromium can crystallize in the same system, the friction coefficient is obviously higher because the (100) plane is parallel to the sample surface.