Differential sintering in ceramic injection moulding: particle orientation effects

Powder Injection Molding of Metal and Ceramic Parts

“…Depending on the material, debound parts or "brown parts" are sintered at temperatures ranging from 1200 to 1600 °C. It is essentially a removal of pores, accompanied by growth and strong adhesion among the adjacent particles, causing the retraction of the product whose dimensions usually reduce between 14 and 20% (Gonçalves, 2001;Krug, 2002;Tandon, 2008). Therefore, green parts are oversized to compensate for the sintering shrinkage.…”

“…One of the main components is termed backbone, which is a thermoplastic polymer that supports and maintains the shape of the molded part until the last stages of debinding (Thomas-Vielma et al, 2008). As examples of currently used backbones, it is possible to mention ethylene vinyl www.intechopen.com acetate (EVA), polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene glycol (PEG), polymethyl methacrylate (PMMA) among others (Ahn et al, 2009;Chuankrerkkul et al, 2007;Krug et al, 2002;Thomas-Vielma et al 2008;Yang et al, 2002) (Fig. 5).…”

“…Nevertheless, care must be taken when handling nano powders since they can be explosive or can easily oxidize; therefore most of the time powder metallurgy utilizes particles in the 1 to 45 m range (Hartwig et al, 1998). In particular, for metal injection molding the mean particle size ranges from 5 to 15 m (Krug et al, 2002). This type of size particles can generally be achieved in ball mills, rotary mills, planetary mills, jet mills, vibrating grinders, stampers and crushers (Schrader et al, 2000).…”

Production of alumina parts by powder injection molding with a binder system based on high density polyethylene

“…Binder system for injection molding of alumina can be grouped according to the major component used: paraffin wax (PW), 5 polyethylene glycol (PEG), 6 ethylene-vinyl acetate copolymer (EVA), 7 polystyrene (PS), 8 polypropylene (PP), 9 low density polyethylene (LDPE), 10 polyoxymethylene (POM) 11 and agarose. 12 Systems based on waxes often exhibit binder-powder separation, agglomeration, poor green strength and there is higher risk for distortion during debinding.…”

Effect of Polymer Crystallinity on Morphology in Ceramic Injection Molding

“…During the course of a comprehensive study of large section injection molding, 3,4,6,29 spherulitic structures were seen in sections Ͼ15 mm thickness. The present work investigates the consequences of syneresis for the quality of moldings.…”