Jinyong Xu

Effects of various power process parameters on deposition efficiency of plasma-sprayed Al2O3-40% wt.TiO2 coatings

To investigate effects of various power process parameters on deposition efficiency, Al2O3-40% wt. TiO2 is selected as raw material to be coated on Q235 steel substrate by air plasma spraying. Different variables of spraying current and voltage are designed, whose spraying power is from 12.8 KW to 16.8 KW and increment step is 0.8 KW. Deposition thickness is proposed as a simple method to characterize the deposition efficiency of coatings. Analysis of variance is used to observe the difference between two adjacent groups. It is shown that deposition efficiency increases with the increase of spraying current; by and large, it firstly rises and then decreases with the increment of spraying voltage. However, the effects of increasing the latter are much stronger on deposition efficiency.

Effects of Cr-Mo Infiltration Source Structure on the Thickness of Alloy Layer by Double Glow Plasma Surface Metallurgy Technology

To strengthen the growth characteristics of layer on Q235 steel, a new source structure of Cr-Mo infiltration was proposed by plasma surface metallurgy technology. Comparative experiments were carried out on source polar of scrubbing brush structure and barrel-shaped structure respectively. The results indicated that the thickness of layer increased obviously on source polar of scrubbing brush structure. The good effect of source polar of scrubbing brush structure was analyzed from the angle of glow discharge.

Preparation of Al2O3/TiO2-containing Coating on Aluminium Alloys by Micro-arc Oxidation

TiO2-containing ceramic coatings were deposited on the surface of aluminium alloys by micro-arc oxidition. Surface and cross-section topograph of ceramic coating were observed using scanning electron microscopy (SEM). The phase composition of ceramic coating was analyzed by X-ray diffraction (XRD). The results showed that ceramic coating surface became smoother, whereas micro pores decreased and outer loose layer became compact as under compact layer. The phase analysis of ceramic coating showed that it consisted of a mixed phase, which mainly contained α-Al2O3 (inner layer) and γ-Al2O3 phase (outer layer) as well as a small quantity of Anatase and Al2TiO5. The outer mixed phase was compact and homogeneous. The wearing experiments indicated that TiO2-containing ceramic coating had well antiwear behavior. The friction coefficient of ceramic coating in lubrication basically ranged from 0.20 to 0.30, which was lower than Al2O3 coating. It also indicated that Al2O3/TiO2 coating had a tiny wearing capacity at a speed of 0.1 m/s and a load of 2 N in air.