The effective area of the car bottom of the large-scale trolley heat treatment furnace in the Northern Machinery Plant of the machinery manufacturing company of Anshan Iron and steel company is 82 ㎡. When the furnace infiltrates the blast furnace bell, the furnace bottom reaches 1200 ℃. The furnace is 8m wide.

Before the transformation, the furnace top material is phosphate heat-resistant concrete precast block. Under high temperature treatment, the service life of precast block is half a year, and its damage is mainly fracture. The reason for the fracture is the poor resistance to rapid cooling and thermal shock.

In 1987, the furnace roof was reconstructed with a full fiber composite structure, and the furnace wall was clay brick masonry with 30mm thick polycrystalline mullite fiber.

The working layer of the furnace is made of l40mm thick polycrystalline mullite fiber. Considering that the temperature is 1200 ℃, the glassy refractory fiber can not adapt to the temperature conditions. The polycrystalline mullite is directly in contact with the flame to protect the glass fiber.

It saves the cost and speeds up the work process.