Sintering Characteristics

Hahn H, Logas J and Averback R S 1990 Sintering characteristics of nanocrystaiiine Ti02 J. Mater. Res. 5 609... 

Tables 1 to 5 summarize the sintering characteristics of borides of groups III A to VIA transition metals.

Table 1. Sintering Characteristics of Borides of Rare-Earth Metals... 

Table 2. Sintering Characteristics of Diborides of Group-IV Metals (TiBj... 

Corbin SF, Lee J, and Qiao X. Influence of green formulation and pyrolyzable particulates on the porous microstructure and sintering characteristics of tape cast ceramics. J. Am. Cer. Soc. 2001 84 41 17. 

This unusual reaction has not been reported previously, however, a number of studies have demonstrated the formation of analogous structures when platinum/alumina specimens were heated to temperatures in excess of 8009C. Baker and co-workers [23] using the CAEM technique to study the sintering characteristics of platinum on alumina in oxygen observed spectacular transitions in the appearance of the specimens at temperatures in excess of 800°C. The metal particles initially spread on the alumina to from diffuse islands and then quite suddenly reconstructed to produce well defined dense shapes. Sprys and Mencik [24] found the same effect when platinum/alumina specimens were subjected to intense electron beams within the electron microscope and characterized the structures as the intermetallic compound PtaAl from electron diffraction analysis. 

The ramifications of this phenomenon on the sintering characteristics of a system where there are only weak interaction forces between the particles and the support become distinct. At temperatures below the Tammann temperature particle growth takes place by the atomic migration mode, and, when this temperature is exceeded, the dominant mode of sintering switches to crystallite migration. 

A variety of properties of the flux must be controlled, including fusion characteristics (fusion temperature range and sintering characteristics), insulation characteristics, flow properties of the powder, viscosity of the molten flux, and non-metallic absorption ability. The viscosity influences the consumption rate of flux, heat transfer in the mold, and non-metallic dissolution rate, and has been the subject of published and unpublished work over the last ten years. 

Ruys, A.J., Sorrell, C.C., Brandwood, A., and Milthorpe, B.K. (1995) Hydroxyapatite sintering characteristics correlation with powder morphology by high resolution spectroscopy. J. Mater. Sci., 14, 744-747. 

The sintering characteristics of quicklimes are influenced by impurities. It is reported [15.1] that the presence of high levels of sodium, either in the limestone, or added to the stone as a solution of sodium chloride or sodium carbonate, reduces sintering of some limes [15.1j. The effect on lime reactivity does not appear to have been reported. Finely divided silica, alumina and/or iron oxide dispersed in the limestone may increase sintering (see also section 15.5). 

It is also probable that the sintering characteristics of very porous limes produced from micro-porous limestones, such as chalk, differ from those of limes made from dense limestones. 

Although plasma prepared powders could be expected to have interesting applications as ceramic raw materials, little has been published on their sintering characteristics. Experiments conducted using plasma prepared S—AljOj have given disappointing results which can be explained by the removal of grain boundaries... 

Compare the drying and sintering characteristics of Si02 gels prepared by the following two methods ... 

The surface area/weight ratio of the ceramic particles should not exceed 10 m /g, as smaller particles tend to adversely affect the sintering characteristics of the accompanying inorganic binder. Ceramic particles having a surface area-to-weight ratio of 1-5 m /g are generally considered optimum. 

It should have good self-sintering characteristics. 

TABLE 6-10. A COMPARISON OF THE SINTERING CHARACTERISTICS OF SOL-GEL DERIVED AND SOLID-STATE SYNTHESIZED BMT POWDERS (ADAPTED FROM KATAYAMA, 1998)... 

The MCC-spheres loaded with cobalt- and nickel-salts behave more or less the same as the iron- and copper-loaded spheres. At 500°C nickel is already in its reduced state, whereas cobalt is still in an oxidic state. At 600°C cobalt is also fully reduced. The sintering characteristics of nickel and cobalt follow the behavior of copper. Some sintering occurs, but not as much as displayed by iron. 

Nanomatcrials also generate interest because of the specific properties linked to the nanometer size of the particles. Some unusual optical and electrical properties are due to a phenomenon known as quantum confinement. The large surface/volume ratio also leads to the use of some of these materials in catalysis. The excellent sintering characteristics of fine powders are useful in the fabrication of ceramics and composites. The dispersion of small particles in various solvents allows the fabrication of thin films and antireflection coatings, or improvements in the optical performance of mirrors. 

Consider next composites utilizing dispersed phases of mainly hard carbides such as SiC, B C, and especially TIC, mainly in AI2O3 matrices. In contrast to the zirconia-toughened composites discussed above, there is less compatibility between the diffusion and related sintering characteristics of these dispersants and alumina and, hence, they are much less sinterable. This has generally limited sintering of these composites to low volume fractions of dispersants, greater porosity, or both. 

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