Shuttle Kiln Wall Brick Thermal Shock Spalling and Roof Hanger Brick Loosening

Problem Description

Ceramic shuttle kilns are intermittent firing kilns: each cycle goes from room temperature to firing temperature (glaze firing 1200–1250℃, porcelain body firing 1300–1400℃) and back to cooling, repeated many times. The wall and roof refractories face prominent issues:

• Thermal shock spalling: frequent heating/cooling creates thermal stress cracks on high-alumina and mullite brick surfaces, causing layer-by-layer flaking; thinner wall leads to higher heat transfer to the backup lining;
• Roof hanger brick loosening: thermal expansion mismatch between hanger bricks and suspension beams during repeated cycles loosens anchor points; falling bricks damage kiln cars and ware and create hot spots/leakage;
• Alkali/boron atmosphere attack: volatile glaze components (alkali, boron) corrode brick surfaces at high temperature, forming low-melting glassy phases and accelerating surface wear;
• Mechanical impact: kiln car entry/exit and sagger stacking cause impact damage to lower wall bricks.

Consequences: elevated outer wall temperature and heat loss, poor temperature uniformity, higher product defect rate and frequent cold repairs.