In comparison to TiN coatings, CrN coatings exhibit superior cor-rosion and oxidation resistance and lower industrial applications such as cutting tools, molds, automobiles, electronics, micro-machinery and aerospace for their excellent mechanical properties, outstanding wear resistance, good chemical and thermal stability. CrN coatings generally present the highly textured surface with the large grain size, which can be used as the storage for lubricants. Thus, they are considered as an important coating for components which is operating in presence of lubricant. Several researches have been devoted to the tribological performance of CrN coatings lubricated by oil-based lubricants under boundary lubrication. Recently, glycerol has been attracted as an environmentally friendly lubricant. Martin and coauthors obtained an abnormally low coefficient of friction when steel was in contact with steel under lubrication of glycerol and studied the effects of contact pressure, sliding speed and temperature on the friction coefficient. Bouchet and coauthors obtained superlubricity in a ta-C/ta-C friction pair lubricated with pure glycerol [19]. They point out that during the friction, the surface atoms react readily to form a very smooth carbon surface containing OHterminated groups. The superlubricity with a friction coefficient of 0.004 for several hours is also found for steel/ta-c friction pair under lubrication of glycerol. However, there is no research available on tribological properties of glycerol for CrN coatings. In this paper, CrN coatings were deposited on 304 stainless steel substrates at three different process temperatures by DC magnetron sputtering. Their tribological properties in presence of glycerol were evaluated and lubrication mechanism was proposed. CrN coatings were deposited on the surface of stainless steel by DC magnetron technology at different temperatures. Their microstructure, adhesion, mechanical properties, phase structure, composition and chemical valence were studied by using field emission scanning electron microscope, scratch tester, X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The tribological properties of CrN coatings under lubrication byglycerol were investigated by using a micro-friction and wear tester. The results show that excellent lubrication performance of CrN coating under lubrication by glycerol. The action mechanism of glycerol in steel/CrN system is proposed with help of X-ray photoelectron spectroscopy.
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