Surface Modification Mechanism of Stearic Acid to Zirconia Powders Induced by Ball Milling for Water-Based Injection Molding

Abstract

In conventional process of ceramic injection molding, wax‐based binders could only be removed by thermal or organic solvent debinding. Recently, water solvent debinding has appeared as a good alternative owing to its high efficiency and environmental friendliness. In present work, we have demonstrated the surface modification mechanism of stearic acid (SA) to zirconia powders induced by a prior ball‐milling treatment before the blending process. Layers of SA with various thicknesses coated around the zirconia powders have been achieved with different amount of SA after the treatment, agreeing well with the theoretically calculated values. The coating is disclosed to be an esterification occurring between the carboxyl group of SA and hydroxyl group of zirconia surface. It plays an important role in limiting agglomeration of ceramic powders and changing the nature of powder surface from hydrophilicity to hydrophobicity, which decreases the shear viscosity of the feedstock and makes the water‐debound compact process‐compatible with few phase separation. In addition, a significantly faster water‐debinding rate was obtained.

Dispersion and properties of zirconia suspensions for stereolithography

“…The broad band at 3454.8 cm −1 is defined as the stretching vibration peak of hydroxy (O-H). 27,28 It was reported by numerous researches that some oxide powders, such as alumina, silica, and zirconia typically have hydroxy group on their surface which can account for their hydrophilic nature. 22 Figure 6C Figure 6B is the FT-IR spectrum of the powder modified with 3.5 wt% DISPERBYK-103, after centrifuged using ethanol at 10 000 rpm and dried at 60°C for 24 hour.…”

Debinding Mechanisms in Thermoplastic processing of a Ba0.5Sr0.5Co0.8Fe0.2O3−δ‐ Stearic Acid–Polystyrene Mixture

“…The weak shoulder around 1500 cm −1 may be related to the asymmetric stretching mode of the carboxylate group (COO). The CH 2 stretching frequencies are shifted to slightly higher frequencies compared to pure SA, which is indicative of solid‐like packing of the alkyl chains, similar to crystalline SA 16b. 18 For thicker coatings (9 mono BSCF), the carbonyl band reappears, indicating the presence of physisorbed SA with non‐modified carboxylic heads.…”

Synthesis of Surface‐Functionalized Titania Particles with Organophosphorus Coupling Agents by Reactive Milling

“…For example, zirconia powder was milled prior to functionalization with stearic acid; this treatment by ball milling resulted in an increase in the number of hydroxyl groups on the surface of the zirconia, which is important for functionalization because stearic acid binds through esterification with these groups. [14] In this study we investigated reactive milling processes by applying strongly surface-binding phosphonates as additives and titania as inorganic pigment. The goal was the in situ surface functionalization of the final products with an organophosphorus coupling agent.…”