Both castable and paint spraying are important types of unshaped refractories, and there are some significant differences in composition, construction methods, properties and application fields. The following is a detailed comparison between castable and paint spraying:

I. Definition and Basic Characteristics

Definition of castable: castable is a mixture of refractory aggregate, powder and binder. During construction, liquid (usually water) is added and stirred into slurry, which is molded by pouring.

Basic characteristics: it has high strength and good high temperature performance, and it needs curing and baking after construction to achieve the best performance.

Paint spraying's definition: paint spraying is a kind of slurry that can be sprayed from unshaped refractory materials and sprayed onto the construction surface by a spray gun to form a refractory layer.

Basic characteristics: fast construction speed, rapid formation of refractory layer, suitable for large-scale construction and complex shape of equipment lining.

II. Composition and Proportion

Composition of castable: It is usually composed of refractory aggregate (such as high alumina clinker, corundum, etc.), fine powder (such as aluminate cement, silica fume, etc.) and binder (such as aluminate cement, phosphate, etc.).

Proportion: the proportion of aggregate and powder is adjusted according to specific needs, usually aggregate accounts for 60%-70% and powder accounts for 30%-40%. The dosage of binder is generally 5%-10%.

Paint spraying composition: The composition of paint spraying is similar to that of castable, but it usually contains more binders and thickeners to improve the adhesion and workability of the slurry.

Proportion: The ratio of aggregate and powder in paint spraying is similar to that of castable, but the dosage of binder and thickener is usually higher to ensure that the slurry will not flow during spraying.

III. Construction Methods

Construction steps of castable:

Stir: mix dry powder with liquid (usually water) in proportion and stir evenly.

Pouring: The stirred slurry is poured into the mold and compacted by vibration or manual ramming.

Maintenance: After casting, proper maintenance (such as covering with plastic film to keep moisture) is needed.

Baking: After curing, bake to remove moisture and improve strength.

Features: The construction process is complicated, but the molding accuracy is high, which is suitable for the parts that need precise molding.

Paint spraying construction steps:

Pulping: paint spraying and liquid (usually water) are mixed in proportion and stirred evenly.

Spraying: use a spray gun to spray the slurry onto the construction surface to form a refractory layer.

Drying: after spraying, naturally dry or bake properly.

Features: The construction speed is fast, and it is suitable for large-scale construction and complex-shaped equipment lining, but the thickness is thin, and it usually needs to be sprayed many times.

IV. Performance characteristics

Strength of castable: It has high room temperature strength and high temperature strength, and is suitable for load-bearing parts.

Corrosion resistance: according to different components, it has good acid or alkaline corrosion resistance.

Thermal shock resistance: Thermal shock resistance is good, but it needs to be further improved through design and construction optimization.

Thickness: Generally, the thickness is relatively thick, which is suitable for parts requiring high strength and fire resistance.

Paint spraying strength: The strength is relatively low, but it can be improved by spraying for many times and optimizing the composition.

Corrosion resistance: the corrosion resistance is better, but not as good as castable.

Thermal shock resistance: Good thermal shock resistance, suitable for parts with frequent temperature changes.

Thickness: usually thin, suitable for parts that need rapid construction and lightweight design.

V. Application fields

Castable

Application fields: metallurgical industry: blast furnace, ladle, tundish, taphole, etc.

Building materials industry: cement rotary kiln, glass melting furnace, etc.

Chemical industry: cracking furnace, fertilizer furnace, etc.

Features: Suitable for parts requiring high fire resistance, high strength and corrosion resistance.

Paint spraying application areas:

Metallurgical industry: blast furnace lining, ladle lining, etc.

Building materials industry: cement kiln preheater, cooler, etc.

Chemical industry: cracking furnace lining, etc.

Features: It is suitable for large-scale construction and complex-shaped equipment lining, which can quickly form a refractory layer and reduce construction time.

VI. Summary of Advantages and Disadvantages

Advantages of castable:

High strength: It has high strength at normal temperature and high temperature.

High fire resistance: able to withstand high temperature environment.

Good corrosion resistance: according to different components, it has good acid or alkaline corrosion resistance.

High molding precision: suitable for parts that need precise molding.

Disadvantages:

Complicated construction: The construction process is complicated, which requires mixing, pouring, curing and baking.

Long construction time: the long curing and baking time affects the rapid operation of the equipment.

Advantages of paint spraying:

Fast construction speed: it can quickly form a refractory layer and is suitable for large-scale construction.

Strong adaptability: suitable for complex shape equipment lining.

Good thermal shock resistance: suitable for parts with frequent temperature changes.

Disadvantages:

Low strength: the strength is relatively low, but it can be improved by spraying for many times and optimizing the composition.

Thin thickness: it usually needs to be sprayed several times to achieve the required thickness.

High requirements for construction equipment: professional spray gun equipment and operators are needed.

VII. Summary

Both castable and paint spraying are important unshaped refractories, each with its own characteristics and applicable scenarios. The castable is suitable for the parts that need high refractoriness, high strength and corrosion resistance. The construction process is complicated, but the molding accuracy is high. Paint spraying is suitable for large-scale construction and complex-shaped equipment lining, with fast construction speed and good thermal shock resistance, but relatively low strength. In practical application, suitable materials and construction methods should be selected according to specific needs to ensure the safe operation and efficient production of equipment.