Sintering

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Guo-jun Zhang - One of the best experts on this subject based on the ideXlab platform.

  • pressureless densification and mechanical properties of hafnium diboride doped with b4c from solid state Sintering to liquid phase Sintering
    Journal of The European Ceramic Society, 2010
    Co-Authors: Guo-jun Zhang
    Abstract:

    Abstract A pressureless Sintering process, using a small amount of boron carbide (≤2 wt%) as Sintering aid, was developed for the densification of hafnium diboride. Hafnium diboride ceramics with high relative density were obtained when the Sintering temperature changed from 2100 °C to 2350 °C. However, the Sintering mechanism was varied from solid state Sintering (SSS, below 2300 °C) to liquid phase Sintering (LPS, above 2300 °C). Boron carbide addition improved densification by removing the oxide impurities during solid state Sintering and by forming a liquid phase which was well wetting hafnium diboride grains during liquid phase Sintering process. The different roles of B 4 C on the microstructure development and mechanical properties of the sintered ceramics were investigated.

  • Pressureless densification and mechanical properties of hafnium diboride doped with B4C: From solid state Sintering to liquid phase Sintering
    Journal of the European Ceramic Society, 2010
    Co-Authors: Ji Zou, Guo-jun Zhang, Yan Mei Kan
    Abstract:

    A pressureless Sintering process, using a small amount of boron carbide (≤2wt%) as Sintering aid, was developed for the densification of hafnium diboride. Hafnium diboride ceramics with high relative density were obtained when the Sintering temperature changed from 2100°C to 2350°C. However, the Sintering mechanism was varied from solid state Sintering (SSS, below 2300°C) to liquid phase Sintering (LPS, above 2300°C). Boron carbide addition improved densification by removing the oxide impurities during solid state Sintering and by forming a liquid phase which was well wetting hafnium diboride grains during liquid phase Sintering process. The different roles of B4C on the microstructure development and mechanical properties of the sintered ceramics were investigated. © 2010 Elsevier Ltd.

Donald Liebenberg - One of the best experts on this subject based on the ideXlab platform.

  • Improved understanding of the spark plasma Sintering process
    Journal of Applied Physics, 2015
    Co-Authors: Dale Hitchcock, Roger Livingston, Donald Liebenberg
    Abstract:

    The process by which spark\nplasma\nSintering produces high densification of powder specimens is examined to determine the role of sparks and plasma. Measurements are reported of the electromagnetic emission during the pulsing current using the state-of-the-art Tektronix MDO4104B-6 to obtain voltage vs time and simultaneously radio frequency (rf) emission in selected power vs frequency regions. The results show strong rf emission over the selected frequency region 0–160 kHz during pulsing and nearly an order of magnitude decrease of power during pulsing but in the gap (no pulse). These measurements showed no rf emission dependence on the electrical conductivity of the specimen or with current levels between 0–500 A and support the conclusion that no sparking or plasma production takes place in the specimen. The steep slope of the current vs time profile is demonstrated to produce the rf emission in a manner described by Hertz and is suggested to provide forces on the Sintering\nmaterial that encourage densification.

Zh R Yuan - One of the best experts on this subject based on the ideXlab platform.

  • mechanical properties phases and microstructure of ultrafine hardmetals prepared by wc 6 29co nanocrystalline composite powder
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2005
    Co-Authors: Gangqin Shao, Xinglong Duan, Zh R Yuan
    Abstract:

    WC–6.29Co nanocrystalline composite powder prepared by spray thermal decomposition–continuous reduction and carburization technology was consolidated by spark plasma Sintering (SPS), spark plasma Sintering with hot isostatic pressing (HIP), vacuum Sintering and vacuum Sintering with hot isostatic pressing (HIP). The mechanical properties, phases and microstructure of WC–6.29Co hardmetals prepared by different processes were researched. The results show that WC–6.29Co ultrafine cemented carbide consolidated by spark plasma Sintering with hot isostatic pressing can reach 99.0% relative density, and transverse rupture strength (TRS) is more than 2740 MPa, Rockwell A hardness (HRA) is more than 93.8, the average grain size is less than 400 nm, and WC–6.29Co ultrafine cemented carbide with excellent properties is achieved. Although specimens consolidated by spark plasma Sintering can reach 99.1% relative density, Rockwell A hardness is more than 94, but transverse rupture strength (TRS) is very low. Compared with specimens prepared by spark plasma Sintering, there are no eta phases in specimens consolidated by spark plasma Sintering with hot isostatic pressing. Furthermore the average grains size of specimens prepared by vacuum Sintering or vacuum Sintering with hot isostatic pressing is coarser than that of specimens prepared by spark plasma Sintering with hot isostatic pressing, but mechanical properties are lower than that of specimens prepared by spark plasma Sintering with hot isostatic pressing. Spark plasma Sintering with hot isostatic pressing can not only decrease the average grain size of sintered specimens, but also increase mechanical properties of WC–6.29Co ultrafine cemented carbide. The specimens prepared by spark plasma Sintering with hot isostatic pressing have better properties than those prepared by spark plasma Sintering, vacuum Sintering or vacuum Sintering with hot isostatic pressing.

Zhijian Shen - One of the best experts on this subject based on the ideXlab platform.

  • Warm pressing of zirconia nanoparticles by the spark plasma Sintering technique
    Scripta Materialia, 2008
    Co-Authors: Martin Trunec, Karel Maca, Zhijian Shen
    Abstract:

    Zirconia nanoparticles were densified by pressureless Sintering and spark plasma Sintering (SPS). The evolution of relative density and pore size distribution in powder compacts during these Sintering processes were compared. It was found that pore size increase was suppressed during SPS and that this facilitated the densification. The combined Sintering process (low-temperature pre-Sintering by SPS followed by pressureless Sintering) was performed to confirm the advantage of the low-temperature SPS technique (referred to as SPS warm pressing). © 2008 Acta Materialia Inc.

Monika Willertporada - One of the best experts on this subject based on the ideXlab platform.

  • effect of particle size and heating rate in microwave Sintering of 316l stainless steel
    Powder Technology, 2014
    Co-Authors: Okan Ertuğrul, Hoseon Park, Kazim Onel, Monika Willertporada
    Abstract:

    Abstract The work evaluates the effect of heating rate in microwave Sintering, and the effect of particle size of 316L powders in microwave and conventional Sintering processes. The powders of 316L stainless steel were compacted by uniaxial press at 700 MPa, and sintered at 1250 °C for 1 h by means of conventional Sintering and microwave Sintering. The Sintering atmospheres were Ar/H2 95/5% for conventional Sintering and Ar/H2 90/10% for microwave Sintering. Mechanical properties were evaluated using tensile tests. The samples were characterized by optical microscopy and SEM. The porosity levels were determined using image analysis software. Microwave Sintering yields fully recrystallized microstructure different from conventional Sintering, however no difference in distribution and shape of pores was noticed. Heating rate in microwave Sintering affects densification, tensile strength and elongation. Moreover, the use of fine powders improves physical and mechanical properties of the samples sintered by both methods.