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3.Centrifugal cast composite ceramic tube
This process adopts the method of self-propagating centrifugal casting, which mainly uses the chemical reaction of the substance itself to generate high temperature by exothermic combustion and synthesize new substances in the process of combustion wave propagation.
The ceramic surface of the ceramic composite pipe formed by this method replaces the ceramic layer. Compared with carbon steel and manganese steel pipes, the wear resistance is improved to a certain extent, but because the reaction temperature is not high (average does not exceed 1200 ° C), it is also oxidized. Aluminum, but the high temperature phase alumina and low temperature phase alumina are very different in terms of strength, hardness and density. Due to the short reaction time, the low temperature phase alumina and molten iron were not completely centrifuged, resulting in a dense ceramic layer, loose particles and low hardness. The wear-resistant elbow is lining 95 ceramics, the alumina content is not less than 95%, and all of them are high-temperature phase α-Al2O3, and the sintering temperature is as high as 1670 ° C to ensure the material quality. Judging from the actual anti-wear effect, the durable time of the wear-resistant elbow is more than 5 times that of the composite ceramic elbow.
Moreover, the technology of centrifugal casting of composite ceramic pipes determines that they are not suitable for elbows and small and large heads. Under ordinary technical conditions, composite ceramic pipes can only be made into straight tubes. To make elbows or small and large heads, straight tubes must be divided into several Section welding, the inner wall of the elbow and the large and small head after molding is not a streamlined structure, which hinders material transportation and reduces equipment output.
At the same time, the ceramic tube produced by this process has many micro-cracks, is brittle and brittle, and is easy to fall off and fail locally, and cannot be repaired after falling off.
In addition, from the perspective of the bearing capacity of the entire boiler, cast steel elbows and composite ceramic elbows all win by weight and thickness. Some elbows have a wall thickness of more than 40 millimeters. From the perspective of the unit design, no doubt Hanger increases weight and shortens service life.
In other words, the price of an alloy elbow is twice that of a wear-resistant ceramic elbow. With the cost of an alloy elbow, you can buy two wear-resistant ceramic elbows. The service life of the wear-resistant ceramic elbow is this alloy. 2-3 times the elbow, use the price-to-life ratio, that is, use a 1/5 alloy elbow to buy a wear-resistant ceramic elbow.