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Material damage caused by the attack of particles entrained in a fluid system impacting on a surface at a high speed is called 'erosive abrasive wear'. Carbon steels are the most common ones used in the fabrication and construction of boilers and furnaces. Typical erosive abrasive wear situations encountered in boilers are caused by the impact of hard particles such as ash and clinker entrained in flue gases. These situations can lead to serious damage. Engineering components encountering erosive abrasive wear conditions during operation can be improved by hardfacing with a wear resistant material. In this paper an attempt has been made to analyse in detail the effects of different experimental parameters such as specimen temperature, standoff distance, orifice diameter, air pressure and abrasive particle size on the erosive abrasive wear behaviour of cobalt based alloy (stellite) surface produced by plasma transferred arc hardfacing process. It is found that air pressure caused a predominant effect on the wear rate of a hardfaced surface, compared to other variables. Both experimental and statistical investigations show that the wear resistance of the cobalt based alloy (stellite) surface is four times better than that of the substrate (carbon steel).

Abrasive slurry wear is generally defined as a mechanical interaction in which the material becomes lost in a surface that is in contact with moving particles, such as laden liquid. Slurry wear abrasion occurs in extruders, slurry pumps, and pipes that carry the slurry of minerals and ores in mineral processing industries. The life of the components used under slurry abrasion conditions is governed by the process parameters, the properties of the abrasive particles in the slurry, and the material properties. This paper analyses in detail the effects of operating variables, such as abrasive particle size, slurry concentration, speed of rotation, and slurry bath temperature, on the abrasive slurry wear behavior of a iron based alloy (stainless steel), cobalt based alloy (stellite), and nickel based alloy (colmonoy) surfaces produced by a Plasma Transferred Arc (PTA) hardfacing process. Of the four variables considered in this investigation, it was found that the slurry concentration had a predominant effect on the wear rate of hardfaced surfaces compared to the other variables. Microstructural analyses of the worned surfaces were carried out using SEM. Both the experimental and mathematical investigations showed that the wear resistance of an iron based alloy was 4 times better than the base metal. Similarly, the cobalt based alloy exhibited a 3 times higher wear resistance while the nickel based alloy showed a 2 times higher wear resistance compared to the base metal (carbon steel).

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Control of dilution is important in hardfacing, where typically low dilution is desirable. At present, majority of the fabrication industries use shielded metal arc welding (SMAW), gas metal arc welding (GMAW), gas tungsten arc welding (GTAW), and submerged arc welding (SAW) processes for hardfacing purposes. In these processes, the percentage of dilution level is higher, ranging between 10-30%. In plasma transferred arc (PTA) hardfacing, a solidified metallurgical bond between deposit and substrate is obtained with minimum dilution (less than 10%). This article highlights the application of response surface methodology (RSM) to predict and optimize the percentage of dilution of nickel based hardfaced surface produced by PTA process. The experiments were conducted based on five-factor, five levels central composite rotatable design with full replications technique and mathematical model was developed using RSM. Further, the RSM is used to optimize the process parameters that yield the lowest percentage of dilution.

Wear by slurry abrasion occurs in extruders, slurry pumps and pipes carrying slurry of minerals and ores in mineral processing industries. The wear life of components used under slurry abrasion conditions is governed by process parameters, properties of abrasive particles in slurry and material properties. In this paper, the effect of operating variables such as abrasive particle size, slurry concentration, speed of rotation and slurry bath temperature on abrasive slurry wear behaviour of nickel based alloy (Colmonoy) surface produced by PTA hardfacing process has been analysed in detail. From this investigation, it is found that the wear resistance of Colmonoy hardfaced surface is two times better than the substrate (carbon steel).

Dry sliding wear occurs when two bodies are in sliding contact. During the process of sliding, fragments may be pulled out from one surface and they may stick on to the other. Later on, these may get transferred back or may become loose wear particles. This paper reports the effects of different experimental conditions on the dry sliding wear behaviour of nickel based alloy (Colmonoy) surface produced by plasma transferred arc (PTA) hardfacing process. The wear test was conducted in a pin on roller wear testing machine, under constant sliding distance of 1 km. Mathematical models were developed to estimate wear rate incorporating rotational speed, applied load and roller hardness using statistical tools such as design of experiments, regression analysis and analysis of variance. It is found that the wear resistance of the PTA hardfaced nickel based alloy (Colmonoy) surface is five times better than that of the substrate (carbon steel).