Low-temperature Sintering Technology Research Articles

Reuse of hazardous calcium fluoride sludge from the integrated circuit industry

The Chinese integrated circuit industry has been transformed from a small state-owned sector into a global competitor, but chip manufacturing produces large amounts of calcium fluoride sludges (CFS). In China, landfill is a current option for treating CFS. In order to solve the problem of unavailable landfill sites and prevent fluorine from dissolved CFS polluting water sources, CFS was tested as a component for a ceramic product made with sodium borate, sodium phosphate and waste alumina using a low-temperature sintering technology, and the effects of various factors on characteristics of the ceramic were investigated to optimize the process. The best sintering temperature was controlled at 700°C, and the optimal raw material ratio of the ceramic was 11% sodium borate, 54% sodium phosphate, 30% CFS and 5% waste alumina. The CFS ceramic was characterized by a morphological structure and X-ray diffraction. The results indicated that CFS was transformed into Na2Ca(PO4)F as an inert and a main crystalline phase in the ceramic, which was enclosed by the borophosphate glass. Toxicity characteristic leaching procedure, corrosion resistance and compressive strength tests verified CFS ceramic as a qualified construction ceramic material, and the fluorine from CFS was solidified in the inert crystalline phase, which would not be released to cause secondary pollution. This novel technology not only avoids the CFS hydrolyzing reaction forming harmful hydrofluoric acid gas at 800°C and above, but also produces high-performance ceramics as a construction material, in accordance with the concept of sustainable development.

Recycling of calcium fluoride sludge as ceramic material using low temperature sintering technology

The Chinese integrated circuit industry has been transformed from a small state-owned sector into a global competitor, but chip manufacturing produces large amounts of calcium fluoride sludge (CFS). The current treating method is landfill in China. In order to solve the problem of unavailable landfill sites and the dissolved CFS polluting water sources, CFS was tested as a component for a ceramic product made with sodium borate, sodium phosphate, and waste alumina using a low temperature sintering technology. The ceramic was characterized by X-ray diffraction (XRD), microstructure, compressive strength. XRD and microstructure analyses verified that CFS was transformed into Na2Ca(PO4)F as an inert crystalline phase in ceramic, which is enclosed by the borophosphate glass liquid phase. Toxicity characteristic leaching procedure and corrosion resistance tests verified that fluorine from CFS was solidified in the inert crystalline phase, which did not release to cause secondary pollution. This novel technology produces high-performance ceramic as a construction material, in accordance with the concept of sustainable development.

Electrical Properties of Low Temperature Sintered Piezoceramics

In general, commercial PZT piezoceramics are sintered at temperature above 1200°C. Here, one low-temperature sintering technology was developed for PZT piezoceramics by adding perovskite-type ferroelectrics with low sintering temperature, alternative to adding non-piezoelectric low-melting glass or eutectic oxides. Through solid state reaction mechanism, very densified piezoceramics of (Pb0.95Sr0.05)(Zr0.53Ti0.47)O3 with 0.6PbTiO3–0.3Bi(Zn0.5Ti0.5)O3–0.1BiFeO3 as sintering additive were obtained below 1050°C. The phase of (Pb,Bi,Sr)(Zr,Ti,Zn,Fe)O3 solid solution piezoceramics was demonstrated to be single-phased perovskite structure and the measurements of dielectric, ferroelectric and piezoelectric properties showed good piezoelectric performance equivalent to PZT-8.

Investigation of the Low Temperature Sintering Technology of NiCuZn Ferrite with Different Additive

Investigation of the Low Temperature Sintering Technology of NiCuZn Ferrite with Different Additive

High-Temperature Operation of SiC Power Devices by Low-Temperature Sintered Silver Die-Attachment

In this paper, we present the realization of high-temperature operation of SiC power semiconductor devices by low-temperature sintering of nanoscale silver paste as a novel die-attachment solution. The silver paste was prepared by mixing nanoscale silver particles with carefully selected organic components which can burn out within the low-temperature firing range. SiC Schottky diodes were placed onto stencil-printed layers of the nanoscale silver paste on Au or Ag metallized direct bonded copper (DBC) substrates for the die-attachment. After heating up to 300degC and dwell for 40 min in air to burn out the organic components in the paste and to sinter the nanoscale silver, the paste consolidated into a strong and uniform die-attach bonding layer with purity >99% and density >80%. Then the die-attached SiC devices were cooled down to room temperature and their top terminals were wire-bonded to achieve the high-temperature power packages. Then the power packages were heated up from room temperature to 300degC for high-temperature operation and characterization. Results of the measurement demonstrate the low-temperature silver sintering as an effective die-attach method for high-temperature electronic packaging. An advanced packaging structure for future SiC transistors with several potential advantages was also proposed based on the low-temperature sintering technology.

Development Status of SOFC Cell and Stack Technology at NRC-IFCI

Solid Oxide Fuel Cell (SOFC) development was started at the National Research Council of Canada's Institute for Fuel Cell Innovation (NRC-IFCI) in 2003 with the goal to develop the next generation of SOFC's for Canadian Industry. To accomplish this task, work focused on the development of low temperature cermet and metal supported cells, direct deposition methods, low temperature sintering, seal and stack technology. As of November 2006, 5cmx5cm cermet supported cell performance has been improved to 900 mW/cm2 @ 600{degree sign}C. These components have been incorporated into short stacks developed at IFCI to continue the push to commercialize this technology. At the same time, direct deposition technology has progressed rapidly to the point where metal supported 5x5 cells can be fabricated using sintering temperatures below 850{degree sign}C. Results of this work will be presented, along with the development path at IFCI.