What are the key steps in the manufacturing process of wear-resistant and refractory castables?

The manufacturing process of wear-resistant and refractory castables involves multiple key links such as raw material selection, proportioning design, mixing process, and construction maintenance. The following is a comprehensive review based on search results:

1、 Raw material preparation and proportioning design

Aggregate selection

High hardness materials are mainly used, such as fused alumina (white corundum, brown corundum), silicon carbide, high alumina alumina, etc., accounting for 60% to 70%. The particle size distribution should follow the principle of tight packing (3-4 levels of grading).

Fine powder (≤ 0.088mm) accounts for 30%~40%, including silica micro powder, corundum powder, etc., used to fill the voids in the aggregate and enhance the bonding strength.

Binders and additives

Adhesive: Calcium aluminate cement (low cement system), phosphate or silica sol, with a dosage of 5%~15%, to match the aggregate material.

Admixtures: Steel fibers (to enhance crack resistance), explosion-proof fibers (to prevent baking and cracking), water reducing agents (such as polycarboxylates) to optimize flowability.

2、 Mixed process

Dry mixing and wet mixing

Dry mixing: Dry mix aggregates, powders, binders, etc. for 2-3 minutes until the color is uniform.

Wet mixing: Slowly add 5.5%~6.5% clean water (pH=6~7.5) and wet mix for 3~5 minutes to avoid excessive local moisture or fiber aggregation.

critical control point

The amount of water added needs to be accurately weighed. Excess will reduce strength, while insufficient will affect fluidity.

The mixed slurry should be used up within 30 minutes to prevent initial setting failure.

3、 Pouring and Forming

Templates and Anchors

The template needs to be waterproofed (coated with release agent or asphalt), and the joints should be sealed to prevent leakage of grout.

The anchor is made of heat-resistant stainless steel (such as 1Cr18Ni9Ti), welded firmly and coated with asphalt paint to compensate for thermal expansion.

Compaction by vibration

Layered pouring (each layer ≤ 300mm), using a vibrating rod to "insert quickly and lift slowly" until surface bleeding occurs, to avoid aggregate floating or voids.

Complex parts can be manually compacted or the amount of water can be appropriately increased.

4、 Maintenance and baking

Maintenance stage

Curing with mold for 24-48 hours (temperature ≥ 20 ℃), and natural curing for 3-7 days after demolding.

Baking curve

Stage 1: Heat up from 10~20 ℃/h to 110~115 ℃, and hold for 24~48 hours to remove free water.

Stage 2: Heat up to 350 ℃ at a rate of 15-30 ℃/h and hold for 24-48 hours to remove crystal water.

Stage 3: Heat up to 600 ℃ at a rate of 15-20 ℃/h and bake according to the operating temperature.

5、 Quality Inspection and Packaging

The finished product needs to be tested for density, strength, fire resistance, and other indicators. When packaging, it should be moisture-proof and labeled with a shelf life (usually 6 months).

The core points of the steps are based on the raw material ratio, compact aggregate gradation, low calcification of binders, precise addition of admixtures, and control of water addition after dry mixing. The wet mixing time is ≤ 5 minutes. The construction layer is vibrated, the anchor is thermally compensated, and the template is leak proof and baked in three stages to avoid residual water and cracking

By strictly controlling the above steps, wear-resistant and refractory castables can achieve high wear resistance (wear amount ≤ 10cm ³), high temperature stability (temperature resistance above 1500 ℃) and other performance requirements.