Cracking defect and porosity evolution during thermal debinding in ceramic injection moldings

Powder Injection Molding of Metal and Ceramic Parts

“…Besides improving flowability, such component should be easily removed in early stages of debinding, in general via solvent methods, leaving open pores that will allow the gaseous products of the remaining polymer to diffuse out of the structure (Thomas-Vielma et al, 2008). Even though this low-melting temperature component has an important role in the process, it is worth to mention that the mechanical integrity of the final product is reduced as its proportion increase after certain limits (Tseng & Hsu, 1999).…”

“…In the last stages of debinding, it is due to the open porous created by this second component that the backbone can diffuse out without damaging the structure of the product. If not by these pores, an excessive pressure would easily build up within moldings from the degradation species during burnout, causing distortions and cracks (Tseng & Hsu, 1999).…”

“…These surface-active dispersants normally present a low melting temperature and affinity to preferentially adsorb onto powder surfaces, forming a densely thin outer layer on a particle surface which leads to a more homogeneous packing structure (Chan & Lin, 1995). However, bubbles and cracks were reported to occur as the amount of the surfactants increases, presumably owning to the reduced vaporization temperature since the surfactants are composed of mostly short molecules (Tseng & Hsu, 1999).…”

Direct observation of mould cavity filling in ceramic injection moulding

“…1 It includes four basic steps consisting of mixing the ceramics powder and binder, injection moulding, 1 thermal, solvent 2 or catalytic debinding 3,4 and finally liquid phase or solid state sintering. 5 Injection defects such as porosity, welding lines, 6 warping 7 and even cracks [8][9][10] frequently occur in the injection moulded parts and are commonly related to the binder composition, inhomogeneous mixture, injection moulding parameters and the non-uniform shrinkage during part cooling. This paper presents a detailed analysis of injection process parameters during the ceramics injection moulding, especially focuses on jetting phenomenon.…”

Effect of Injection Molding and Sintering Behaviors on Y-TZP Dental Implants

“…The first and second binder vaporization periods respectively took place at temperatures between 260 to 380°C and 400 to 500°C, as evidenced by the obvious weight changes at these temperatures. Within these temperature periods, the heating rates should be slower to ensure enough time to eliminate the binder [12,13].…”