Various applications of polymers and their composites in erosive wear situations are reported by Pool et al. [3], Kulkarni and Kishore [260] and Aglan and Chenock [261] in the literature. But solid particle erosion (SPE) of polymers and their composites has not been investigated to the same extent as for metals or ceramics. However, Tewari et al. [262] have evaluated the resistance of various types of polymers and their composites to SPE. It is widely recognized that polymers and their composites have poor erosion resistance. Their erosion rates are considerably higher than metals. In some cases that the erosion rates of polymer composites are even higher than that of neat polymers as reported by Häger et al. [263]. Tilly and Sage [264] have investigated the influence of velocity, impact angle, particle size and weight of impacted abrasives on nylon, carbon-fiber-reinforced nylon, epoxy resin, polypropylene and glass-fiber- reinforced plastic.
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It has been reported in the literature that polymers and their related composites are extensively used in erosive wear situations. Consequently, many researchers have investigated the solid particle erosion behaviour of various polymers and their composites. Polymers that have been reported in the literature include polystyrene [265], polypropylene [266, 267], nylon [268], polyethylene [269], ultra high molecular weight polyethylene [270], poly-ether-ether-ketone [271], polycarbonate and poly-methyl-meth-acrylate [272], epoxy [264], bismileimide [273], elastomers [274, 275] and rubber [276]. Barkoula and Karger-Kocsis [185] have also presented a detailed review on important variables in erosion process and their effects on different classes of polymers and composites. Miyazaki and Takeda [277] studied the effect of matrix materials, reinforcement fibers, fiber matrix interface strength, impact angle and particle velocity on the solid particle erosion behaviour of fiber reinforced plastics (FRP). They observed that the erosion rate of a FRP decreases with the increase of the interface strength between matrix material and fibers. Miyazaki and Hamao [278] further carried out another similar study on the erosion behaviour of short fiber reinforced thermoplastic resins with special attention focussed on an incubation period of erosion.
Harsha et al. [279] reported the influence of impingement angles and impact velocities on SPE of various poly-aryl-ether-ketones and their composites with short fiber reinforcement. In another investigation, Barkoula and Karger-Kocsis [280] studied the effects of fiber content and relative fiber orientation on the SPE of glass fiber/polypropylene composites. Tewari et al. [281] studied the influence of impingement angle and fiber orientation and concluded that unidirectional carbon and glass fiber reinforced epoxy composites showed semi- ductile erosion behaviour with the maximum erosion rate occurring at 60° impingement angle. In another study, Arjula and Harsha [282] have discussed the usefulness of the erosion efficiency parameter to identify various wear mechanisms. Few publications by Patnaik et al. [283-288] on erosion wear characteristics of glass-polyester composites filled with different particulate
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fillers suggest that in such hybrid composites, the rate of material loss due to SPE reduce significantly with the addition of hard particulate fillers into the matrix. They have also reviewed extensively on erosion wear characteristics of fiber and particulate filled polymer composites [289]. Panda et al. [290] studied the erosive wear analysis of glass fiber-epoxy reinforced AlN hybrid composites and more recently, Kaundal [291] made a critical review on role of process variables on the SPE of polymer composites. Bagci and Imrek [292] studied solid particle erosion behaviour of a new composite material formed by adding boric acid particles to glass fibers and epoxy resin. Friction and wear behaviour of the polyimide composites at elevated temperature under sliding and erosive conditions have been investigated by Zhao et al. [293]. Zhang et al. [294] investigated on the erosion characteristics of molded carbon fiber composites by sand erosion test using silica particles. Padhi and Satapathy [179, 180] have also reported on the erosion behaviour of blast furnace slag filled epoxy composites with and without glass fiber reinforcement. Recently, Gupta and Satapathy [123] have studied the erosion wear response of borosilicate glass microsphere filled epoxy composites under different test conditions. Mohapatra et al. [295] reported the processing and erosion response of a multiphase composite consisting of epoxy resin reinforced with E-glass fiber and TiC particles. They further investigated the solid particle erosion behaviour of glass-epoxy composites filled with TiC derived from ilmenite [296].
Tsuda et al. [297] studied sand erosion behaviour and wear mechanism of various types of glass fiber reinforced plastics. Rajesh et al. [298] selected a series of polyamides for investigating the effects of chemical structure and hence, mechanical properties on erosive wear behaviour by impinging silica sand particles at various angles and doses. Biswas and Satapathy [176] developed a mathematical model for estimating erosion damage caused by solid particle impact on red mud filled glass fiber reinforced epoxy matrix composites and also found a correlation derived from the results of Taguchi experimental design.
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In a study by Srivastava and Pawar [159], experiments were carried out to study the effects of fly ash filler, impingement angle and particle velocity on the solid particle erosion behaviour of E-glass fiber reinforced epoxy composites. The result showed semi-ductile erosion behaviour with maximum erosion rate at 600 impingement angle. Yang and Nayeb-Hashemi [299] investigated the effects of solid particle erosion on the strength and fatigue properties of E-glass/epoxy composites. Harsha and Jha [300] studied the erosion resistances of neat epoxy, unidirectional glass fiber reinforced epoxy and unidirectional carbon fiber reinforced epoxy as well as bidirectional E-glass woven reinforced epoxy composites. It was found that bidirectional glass fiber reinforced epoxy composites exhibited higher erosion resistance than their unidirectional fiber reinforced counterparts.
2.10 Implementation of Design-of-Experiments and Artificial Neural