Preparation Of The High Temperature Steel Heat Insulation Covered Coating And Its Properties

For the anti-corrosive of the high temperature steel surface,the normal organic coating is hard to resist the temperature at 400℃for a long time.And the normal inorganic heat insulation coating which has high brittleness and low anti-heat shock performance is easy to be break off. Nowadays the temperature of organic heat insulation covered coating which is being researched and used is less than 350℃.The coating is easy to be break off excess this temperature due to the deterioration of the physical mechanical properties and the loss of bond strength.The paper introduces a kind of inorganic heat insulation coating which is successfully developed by overall considering the heat insulation performance,water resisting property and the anti-heat shock performance.This coating which includes sodium silicate adhesive with the mode number of 2.2-2.5 has good hardness but inferior water resistance without curing agent.The water resisting property of the coating is greatly improved by adding the curing agent.Water resisting strength property conservation rate of the coating is up to 70%by adding 1%curing agent. SiO₂ and Al₂O₃ are assistant powder of the coating.SiO₂ can form eutectoid which has fluxing action to coating in high temperature,it can alleviate thermal shock and crack of the coating.Al₂O₃ can accelerate the process of curing and has a good effects on curing.Expanded perlite used to enhance effects on the heat insulation performance.The temperature at the bottom of coating with 2.5cm thickness is about 400℃while the temperature at its surface is about 160℃after adding 1.5%expanded perlite.Fibrous material also has some enhancing effects on heat insulation because fibre can form consecutive network skeleton structure where point contact connections between fibre can't form consecutive access.And this organization structure has good effects on thermal shielding. Adding 320# high temperature resistant filling can greatly improve the anti-heat shock performance of the coating.This is because 320# high temperature resistant filling can reduce internal stress of thermal expansion and contraction and has good thermal conductivity which is useful to the transmission of thermal flux,the reduction of thermal gradient and thermal stress in the interior of materials,the elimination of injury of materials due to thermal shock and decentralization of the stress so as to prevent the coating from losing its effects because of thermal shock.Intensity of the coating has little losses by adding 12% 320# high temperature resistant filling to the coating with the temperature range of 200℃.The retention rate of thermal shock strength of the coating with the temperature range of 400℃can reach about 60%.The anti-heat shock performance of the coating can be improved by adding intensify fibre 205.And the retention rate of thermal shock strength of the coating is 54.5%with adding 2-4cm intensify fibre205.The optimum formula of the inorganic heat-barrier coating is as follow: sodium silicate:40-45%,quartz powder:35-40%,aluminium oxide 4-8%, curing agent P:0.5-1%,expanded perlite:1-1.5%,320# high temperature resistant filling:8-12%,reinforcing fibre 205:0.4-1.2%,kaolin:1-5%. And the best curing process of the coating is as follow:room temperature/ 24h→50℃/24h→80℃/24h→150℃/24h。Synthetical properties of the heat insulation,water resisting and the anti-heat shock can reach to the maximum value of balance.