Sintering rapid

Snowballs are the most common example of sintering. Unless it is very cold, ice will sinter rapidly enough to allow snowballs to be made. 

The discrepancy between the results of Fiederow et al. and of Chu and Ruckenstein may be related to the method used to prepare the catalysts. Thus, Chu and Ruckenstein comment that industrial catalysts sinter rapidly... 

Catalyst was found to sinter rapidly In a 9 1 steam hydrogen atmosphere (25 atmospheres pressure) but, after an initial period, wintering slowed down. The... 

The substrate is coated with a high surface area material, known as a washcoat, which acts as a support for the active component. The support must be able to maintain its surface area under the operating conditions for the catalyst. However, most oxide supports sinter rapidly above 1200°C and transform into low-surface-... 

Perovskites such as LaCo03 and Sr-doped LaCoOa have been investigated extensively as combustion catalysts [17] but, as can be seen from Table 1, these oxides sinter rapidly at 1000 °C giving low-surface-area materials with a low activity on a per gram basis. 

A second difference between the two is the behaviour when the catalysts are fired in air. Claus salt initially decomposes to rhodium metal but in the presence of air is converted to the oxide which sinters rapidly. Thus a worse dispersion of rhodium is observed when Claus salt is fired in air than when it is fired in nitrogen or hydrogen/nitrogen. In the case of rhodium chloride a superior overall rhodium dispersion is achieved and air firing is not so detrimental to dispersion as it is for the ammine complex. These observations can again be explained in terms of the decomposition chemistry of the precursor. Newkirk and McKee (ref. 51) have studied the decomposition of rhodium chloride, both unsupported and supported on alumina,... 

F. E. H. Tay and E. A. Haider, Laser sintered rapid tools with improved smface fish and strength using plating technology. Journal of Material Processing Technology, Vol. 121, pp. 318-322(2002). 

Trapped gas in closed pores often limits densification when sintering witlr a liquid or viscous (glass) phase because rapid material transport tlirough tlie liquid often results in pore closure early in tlie sintering process. 

Prepare a solution of 41 g. of anhydrous palladium chloride (1) in 10 ml. of concentrated hydrochloric acid and 25 ml. of water (as in A). Add all at once 60 ml. of 6iV-sulphuric acid to a rapidly stirred, hot (80°) solution of 63 1 g. of A.R. crystallised barium hydroxide in 600 ml. of water contained in a 2-htre beaker. Add more 6iV-sulphuric acid to render the suspension just acid to htmus (5). Introduce the palladium chloride solution and 4 ml. of 37 per cent, formaldehyde solution into the hot mechanically stirred suspension of barium sulphate. Render the suspension slightly alkaline with 30 per cent, sodium hydroxide solution, continue the stirring for 5 minutes longer, and allow the catalyst to settle. Decant the clear supernatant hquid, replace it by water and resuspend the catalyst. Wash the catalyst by decantation 8-10 times and then collect it on a medium - porosity sintered glass funnel, wash it with five 25 ml. portions of water and suck as dry as possible. Dry the funnel and contents at 80°, powder the catalyst (48 g.), and store it in a tightly stoppered bottle. 

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