Introduction to construction methods for fire-resistant spray coatings
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Time：
2024-01-30
Spray coating construction shall be carried out according to the construction instructions provided by the manufacturer for the specified spray coating number, in order to determine suitable parameters such as wind pressure, water pressure, etc.
Refractory spray coating is a material that is sprayed onto the sprayed surface using a spray gun. The material used for spraying is called refractory spray coating. Spraying is carried out using a sprayer and a spray gun. Refractory coatings are sprayed into the pipeline using compressed air or mechanical pressure to obtain sufficient pressure and flow rate, and then sprayed onto the sprayed surface through a nozzle, forming a solid spraying layer.
The spraying methods of refractory spray coatings are divided into three categories: wet method, dry method, and flame method.
(1) Wet spraying. Wet spraying refers to the spraying of refractory coatings onto the sprayed surface after adding water or liquid binders. Wet spraying can be divided into four types: slurry method, wet method, semi dry method, and pseudo dry method. The last three methods are suitable for spraying furnace construction or repairing furnace lining.
The mud method is to first mix the refractory mixture into mud and then spray it, mainly used for hot spraying to repair the furnace lining; Wet method is to mix refractory mixtures into pumped slurry and then spray them; The semi dry method involves mixing the refractory mixture with a small amount of water and stirring it evenly. When it is transported to the nozzle, the remaining water is added before spraying; The false dry method is to mix the refractory mixture evenly through a mixer, then transport it to the nozzle and add water for spraying.
(2) Dry spraying. Dry spraying refers to directly spraying the mixed refractory coating onto the sprayed surface through a nozzle, mainly used for furnace repair.
(3) Flame spraying. Flame spraying is a process in which a mixed refractory coating is transported to the nozzle by high-speed oxygen flow in a pipeline, and then sprayed out together with combustible gas. The material moves forward during combustion and is sprayed onto the sprayed surface in a molten state. This method is mainly used for hot spraying repair of furnace lining, without damage to the original furnace lining, the spray coating is easy to sinter, and the service life is long.
The technical key of refractory spray coatings and refractory repair materials mainly includes adhesion, bonding, strength, and sintering. This is also a fundamental characteristic that materials should possess, otherwise it will reduce the service life of spray and repair layers. This characteristic is closely related to the material itself, and more importantly, it is constrained by equipment such as spraying machines and construction process parameters, as well as factors such as the state and usage conditions of the sprayed material. These constraints and influencing factors are the basis for selecting refractory spray coatings and refractory repair materials, as well as the key link to obtaining a good spray or repair layer. Therefore, reasonable selection, careful adjustment, and strict control should be made.
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