Sintering ovens

The monolith is now ready for insertion in a sintering oven in order to adjust the final characteristics of the catalyst. This means, for example, that the catalyst will have to be sintered at a temperature above the desired reaction temperature in order to prevent sintering during the reaction, which usually results in a decrease in surface area and deactivation. 

Ovens. PTFE is an excellent thermal insulator. Its thermal conductivity (0.25 W/m K), roughly 2,000 times less than copper, impacts the rate of sintering of a preform. The most common way of delivering heat to a preform is by circulation of hot air. Ideally, the sintering oven is electrically heated for use up to 425 °C and should be equipped with override controllers to prevent overheating. 

An annealing chamber is sometimes installed at the exit of the sintering oven to prevent the coated glass from cooling too rapidly to avoid wetting difficulty during the second pass coating. 

Powder strew process From a reservoir funnel, a powdery bonding agent is applied by a volumetric or strew roller over the complete machine width. It is distributed evenly on the nonwoven fabric led under the strew device. Then the fabric arrives in a sinter oven. 

Powder point process Roller screens or engraving rollers dose the powdery bonding agent on the nonwoven. After that they can be melted together in a sinter oven. 

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