What is the manufacturing principle of wear-resistant refractory bricks?

The manufacturing principle of wear-resistant refractory bricks is to optimize the raw material ratio, particle size distribution, binder selection, and sintering process to form a microstructure with high hardness and high density, thereby improving their wear resistance and high temperature resistance. The following are the specific principles and technical points:

1、 Raw material ratio and component synergy

High hardness main material

Silicon carbide (SiC): With a Mohs hardness of 9.5 and good high-temperature stability (resistance to 1800 ℃), it is the core component of wear resistance.

Corundum (Al ₂ O3): When Al ₂ O3 ≥ 90%, the staggered structure of short columnar corundum crystals and mullite can resist grain slip and improve high-temperature wear resistance.

Composite additives such as graphene and modified carbon nanotubes (acidified and loaded with nano Al ₂ O3/MgO) can enhance matrix dispersibility and bonding strength.

Adhesive system

Phosphate binding: Phosphoric acid reacts with aluminum powder to form aluminum phosphate, which dehydrates and polymerizes at high temperatures to form a chain or network structure, endowing the brick with high strength and wear resistance.

Metal synergy: Molybdenum disulfide (MoS ₂) is combined with low-carbon ferromanganese in a mass ratio of 2:1 to optimize grain boundary bonding and reduce high-temperature wear.

2、 Particle size distribution and densification design

Grading of 'large at both ends and small in the middle'

Coarse particles (3-1mm): as a skeleton support, accounting for 30-40%, resistant to mechanical impact.

Fine powder (<0.1mm): Fill the gaps and wrap around coarse particles, accounting for 20-30%, to improve sintering activity and compactness.

Optimization effect: The apparent porosity can be reduced to below 15%, and the bulk density is ≥ 2.7 g/cm ³.

High pressure forming process

Using a 630-1000 ton press to form, ensuring that the billet is dense and free of layer cracks (pressure ≥ 900 kN).

Trapped material for 24 hours (temperature ≥ 25 ℃) to release gas and avoid the formation of rough surfaces or cracks during compression.

3、 Sintering process and structural strengthening

Segmented firing control

Preheating stage (room temperature -1000 ℃): Slowly raise the temperature (≤ 30 ℃/h) to remove moisture and avoid cracking.

High temperature stage (1000-1700 ℃):

1000-1200 ℃: Generate low melting point liquid phase (such as silicate), promote particle rearrangement.

1500-1700 ℃: Mullite (3Al ₂ O ∝· 2SiO ₂) and corundum crystals form, with a densification shrinkage rate of 2-5%.

Cooling strategy

High temperature zone (>800 ℃) rapid cooling (100-150 ℃/h) suppresses excessive grain growth;

Low temperature zone (＜ 800 ℃) slow cooling (≤ 50 ℃/h) to avoid quartz crystal transformation (573 ℃) leading to cracking.

4、 Performance optimization mechanism

Improved wear resistance

Hardness dominant: The high hardness of SiC or corundum directly resists particle erosion.

Liquid phase lubrication: At medium temperatures (1200-1300 ℃), the viscosity of aluminum phosphate liquid phase is moderate, reducing friction losses.

high-temperature stability

Crystal structure: The eutectic temperature of mullite (melting point 1870 ℃) and corundum (2050 ℃) reaches 1840 ℃ and does not soften at high temperatures.

Antioxidant: Modified carbon nanotubes and graphene can delay the decomposition of SiC in an oxidizing atmosphere.

5、 Typical Applications and Selection

Steel blast furnace tapping groove: Corundum silicon carbide brick (SiC ≥ 90%), resistant to molten iron erosion.

Cement rotary kiln: made of alumina bricks (Al ₂ O3+SiC), resistant to clinker wear.

Glass melting furnace: Electric fused zirconia alumina brick (ZrO ₂ ≥ 33%), resistant to glass liquid erosion.

summary

The manufacturing principle of wear-resistant refractory bricks revolves around the selection of high hardness components, densification structure design, and precise sintering control, achieving performance breakthroughs through multi-scale optimization (nano modification → macro forming). Future trends include the development of nanocomposites (such as plate-like corundum) and environmentally friendly chromium free materials (such as dolomite bricks).