Effect of carbide powder characteristics on the PVT behavior of powder injection molding compounds

Abstract

Effect of powder concentration and particle size distribution of highly filled cemented carbide compounds on their pressure-volume-temperature (PVT) characteristics and thermal properties was investigated. PVT data of compounds containing up to 50 vol.% of powder evaluated on a high-pressure mercury dilatometer reveals that the pressure influences both detected phase transitions, but it causes a different effect on the melting and crystallization of the material only for the higher transition (corresponding to binder components with melting temperatures 100 and 107 °C). The discrepancies in specific volumes at an applied pressure diminish with increasing powder content, whereas melting temperatures -derived from differential scanning calorimetry -remain unaffected. Volumetric thermal expansion coefficient and compressibility are linearly and exponentially, respectively, dependent on pressure. Further, the variance in the particle size distributions of carbide compounds resulted in shifts in both volumetric thermal expansion coefficients and compressibility values.

Effects of particle characteristics on homogeneity of green bodies in powder injection moulding

“…1,25,26 On the contrary, the quality was poor when the particle density was higher than 9 g cm 23 and the particle size bigger than 15 mm. 3,13 We also noticed that the green body prepared with the spherical powders owned the better homogeneity, even the particle sizes were big. 1,5,25 The homogeneity of green bodies prepared with plate-like powders was poor, and defect formation in debinding and sintering was related to the particles, even the particle sizes were small.…”

“…3 Hausnerova et al 3 investigated the morphology of moulded samples by atomic force microscopy, and found that the samples with large particle dimensions or particle densities had less homogenous microstructure. Shivashankar et al 4 used the torgue rheometer to investigate the powder-binder separation phenomena of several feedstocks, and the results confirmed that high powder loading, irregular particle shape or small particle size increased powderbinder separation.…”

“…Several studies clearly indicated that the homogeneity of the green body was significantly influenced by the particle characteristics, including particle size, [3][4][5][6] particle size distribution, [7][8][9][10] particle morphology [11][12][13][14] and particle density. 3 Hausnerova et al 3 investigated the morphology of moulded samples by atomic force microscopy, and found that the samples with large particle dimensions or particle densities had less homogenous microstructure.…”

“…Several studies clearly indicated that the homogeneity of the green body was significantly influenced by the particle characteristics, including particle size, [3][4][5][6] particle size distribution, [7][8][9][10] particle morphology [11][12][13][14] and particle density. 3 Hausnerova et al 3 investigated the morphology of moulded samples by atomic force microscopy, and found that the samples with large particle dimensions or particle densities had less homogenous microstructure. Shivashankar et al 4 used the torgue rheometer to investigate the powder-binder separation phenomena of several feedstocks, and the results confirmed that high powder loading, irregular particle shape or small particle size increased powderbinder separation.…”