Effect Of Zr/Ti Atomic Ratio On Microstructure And Properties Of(TiZr)N Hard Films

The hard films of(Ti Zr)N are deposited on high speed steel substrates by multi arc ion plating technology using the combination of the two targets among the pure Ti target, the pure Zr target and the Ti-Zr alloy target. The(Ti Zr)N films with the varied compositions are deposited by changing the arc electric current and keeping the same bias voltage and the same nitrogen partial pressure. The surface composition and compositions distribution in cross-section, surface and cross-section morphology are measured and characterized using field emission scanning electron microscopy with an energy dispersive X-ray spectroscopy(EDS). The microhardness of the hard films of(Ti Zr)N are measured by nano-indentation. The adhesion between the film and the substrate are measured by Scratch Tester. The phase structures of the(Ti Zr)N are characterized using the X-ray diffraction(XRD). The thermal shock resistance at 600℃ of the films is tested by using SG2-5-12 electric heating furnace.In the present research, the(Ti Zr)N films with the varied Zr content are reached by using different targets and different targets current. The observation of the cross-section of the(Ti Zr)N films shows the thickness values of the films are 1.0~1.3μm. A dense columnar microstructure is obtained in each of the(Ti Zr)N films. The composition distributions in the(Ti Zr)N films appear some regularities. The face-centered cubic structure is determined for each of the(Ti Zr)N films by XRD analysis. The preferential growth orientation is single(111) plane or double planes,(111) and(220).The hardness valuse of the films with the change of the compositions show two maximums and one minimum. The minimum value emerges as the composition of the(Ti Zr)N films is about 50:50 of the Zr/Ti atomic ratio. The adhesion between the film and the substrate is strong. The friction coefficient valus drop in 0.25 ~ 0.55 range. The droplet distribution is less on the surface of(Ti Zr)N films and the droplet size is smaller. The friction coefficient is smaller, and the friction coefficient curve is more smooth. The(Ti Zr)N films surfures have occured the tiny cracks after certain thermal shock sycles at600 ℃/ 15 min. The development and extension of the tiny cracks and the final peeling off are observed with the following tests. The thermal shock test results show that the high temperature oxidation resistance and the thermal shock resistance of the(Ti Zr)N films are not good.