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A novel method to fabricate high-performance Al 2 O 3 Ceramics by indirect Selective Laser Sintering (idSLS) based on particle packing optimization was reported. Al 2 O 3 ceramics with the particle size distribution (PSD) being adjusted based on a particle packing model was prepared with the idSLS method, and the effects of PSD on the macro-performance and microstructure of the idSLSed ceramics part was investigated. Results show that an appropriate PSD of raw material is not only essential to the good SLS formability of powder bed but also contribute to the favorable sintering characteristics of the SLSed green body through an ideal particle packing. The improvement of overall properties including mechanic strength, dimensional accuracy, and surface flatness of the SLSed green body and the final parts were achieved with a fine-tuned PSD exponent. When the raw material has a PSD exponent of 0.5–0.6, the final ceramic parts showed relatively balanced comprehensive properties of bulk density >2.0 g cm−3, linear change <1.4%, fracture strength >3.97 MPa, compressive strength >5.25 MPa and surface altitude difference <148 μm. [ABSTRACT FROM AUTHOR]

In this study, near stoichiometric InGaZnO 4 (IGZO) nano-powders were synthesized by a multistep precipitation method with the ammonia solution used as precipitant at 10 °C. Then cold sintering process (CSP) was applied to benefit the green pellets. In the next step, the green pellets fabricated by CSP and dry pressing process (CP) were pressureless sintered (PLS) at 1200 °C or higher temperature for a scheduled time respectively. The in-situ high temperature optical dilatometric test, XRF, XRD and SEM were carried out and the sintering kinetics was analyzed based on the Master Sintering Curve (MSC) model. The results showed that the holding time for densification of CSP/PLS pellets was about 1 h at 1200 °C, just about 1/5 of CP/PLS ones. MSC model revealed that the sintering activation energy (Qa) of CSP/PLS and CP/PLS were 489.7 KJ /mol and 655.6 KJ /mol respectively. The highest relative density (99.30%) of all sintered pellets was achieved by CSP/PLS process and the optimal process parameters were CSP at 180 °C, 200 MPa and 10 min, and PLS at 1200 °C for 1 h. CSP/PLS effectively reduced the sintering temperature and holding time in comparison with the CP/PLS in this research and previous research. [ABSTRACT FROM AUTHOR]

This paper studied the influence of sintering temperature on composition, density and electrical properties of InGaZnO 4 ceramics synthesized by conventional solid-state reaction technique. Firstly, IGZO powders were prepared by mechanical ball milling of micron-scale In 2 O 3 , Ga 2 O 3 and ZnO mixed powder and the effects of milling time, ball to powder weight ratio (BPR) and dispersant on the properties of mixed powders were investigated by XRD, SEM and laser diffraction particle size analyzer. Secondly, the green compacts formed by mixed powders were sintered at different temperatures (1100, 1200, 1300, 1400 °C) and time (0, 1, 3, 6 h), then the sintering behavior and electrical properties of the compacts were analyzed. The results showed that when the BPR was 10:1 and 2 wt % polyammonium acrylate was used as dispersant, the powder owed the best compression performance and the relative density of the green compact reached 67.14%. Owing to the decomposition of In 2 O 3 , obvious loss of mass phenomenon occurred during sintering process. When the compact was hold at 1400 °C for 150 min, the density of compact reached as high as 99.5%. The lowest resistivity of the compact reached 6.07 × 10−3 Ω cm when the compact was kept at 1400 °C for 3 h. [ABSTRACT FROM AUTHOR]