Plasma Clad Wear And Corrosion Resistant Coatings To Reinforce The Inner Surface Of Drilling Pump Liner

The hard stress with high frequency circulation is loaded of the drilling pump liner in oil industry, and erosion wear influence from drilling fluids with the high hardness quartz grains. The material of drilling pump must have high wear-resistance and fatigue- resistance properties. In view of the situation about low capacity of wear-resistance and short of the service life from the present the drilling pump liner, in this paper, we make coating in order to get surface strengthen with plasma cladding measure from the drilling pump liner. This advanced composite coating from the drilling pump liner should combine well with the substrate, incidentally this coating has coagulated in a short time, so it has excellent hardness and high wear resistance properties. If the drilling pump liners can make a huge improvement of the wear resistance capacity, they will get a long service life.The metal silicide Ti5Si3 has high hardness in ordinary temperature, even in high temperature, it also has the excellent properties of oxidation- resistance, corrosion resistance, adhesive wear-resistance and abrasive wear- resistance. It can be the strengthen phase of the composite coating. In this paper, according to the binary phase diagram of Ti-Si and the ternary phase diagram of Fe-Si-Ti, in consideration of the dilution ratio from the substrate and influence of the atmospheric environment, we make composite coating by Ti intermetallic matrix as the strengthen phase from 37CrMnMo substrate surface in using four different proportion of Fe-Si-Ti mix powder. The microstructure and phase composition of the plasma cladding intermetallic composite coatings were characterized by XRD, OM, SEM and EDS. The graded distribution of micro-hardness was tested in a micro- sclerometer.The room temperature dry sliding wear resistance of the coatings were evaluated under SRV high temperature friction wear test machine. We analyse the wear mechanization in the following time.The composition and micro-structure analysis results revealed that coating with the proportion powder of 20.5Fe28Si51.5Ti (at.%) has a micro-structure characteristic feature. This micro feature is Fe2SiTi phase as the strengthen phase diffusion in Ti5Si4/γ-Fe eutectic matrix phase. It doesn't have a high hardness, because of this coating doesn't have the high hardness metal silicide Ti5Si3 and the hardness number is HV604. Other coatings with the proportions powder of 17Fe34Si49Ti (at.%), 16Fe24Si60Ti(at.%),11Fe33Si56Ti(at.%) all have metal silicide Ti5Si3 as the chief strengthen phase. All these coatings have a high hardness, the number is HV1224, HV1177, HV912. In comparison with substrate phase, the above three coatings wear resistant properties improve 8 times,5.71 times and 5 times. The general trend rule is that the hardness of coating with metal silicide Ti5Si3 is much higher than coating without metal silicide Ti5Si3. In all the coatings including Ti5Si3, one may get high hardness and more excellent wear-resistance with more volume fraction of Ti5Si3, more equality diffusion, much smaller of the granule diameter.