How to construct refractory plastic to achieve zero expansion?
Refractory plastics are easy and fast to construct and are stable in use. If you want the plastic to achieve zero expansion, you need to adopt a zero-expansion design to offset the expansion and contraction of the plastic at high temperatures.
1. Plastic has certain plasticity when the temperature is high
Refractory plastics have certain plasticity when the temperature is high. Zero expansion of plastics means they can withstand drastic changes in kiln temperature and resist frequent furnace shutdowns and temperature rises. Plastic molds can be removed immediately after construction. If it is for maintenance, no oven is needed. It can be put into use directly as the furnace temperature rises.
However, during construction, attention should be paid to the formwork construction to ensure that the deformation of the steel structure and the lining furnace are synchronized. In addition, the anchor bricks must be evenly stressed to avoid breakage and roof collapse during use.
2. Zero expansion design is the description of construction
The zero-expansion design means that during construction, the mold should be set up first to ensure that the construction area is clean, and then the refractory plastic blank should be laid at the ramming area. Only a single layer of material can be laid at a time. The hammer head is downward, and the hammer head is moved and overlapped back and forth to make the plastic Flat, secret room. If the anchor bricks are being constructed, the tamping surface of the refractory plastic should be 16 to 20mm higher than the bottom surface of the anchor bricks. Place the wooden mold on the anchor bricks to straighten it and hammer out the tooth marks. The plastic around the anchor bricks should be pounded tightly.
The construction of refractory plastics should be laid out and pounded layer by layer. Each layer should be shaved and kept at the same height as the construction surface. If there is an interval during the pounding of plastics, plastic sheets should be used to cover the pounded surface. The surface of the material should be shaved during construction during snowy weather. When construction is interrupted for a long time, the joint should be left between the two rows of anchor bricks.
3. Description of plastic used on stove tops
If refractory plastics are used on the stove top, the force direction of the hammer head should be horizontal during ramming, and the joints of the material surface and the working surface of the furnace top should be vertical. The peeling layer must not overlap with the joints of the material surface during the production process; plastics On the top of the furnace, start pounding from the joints of the billet; during construction intervals, cut the material vertically into the furnace shell at right angles and cover it with plastic sheeting to prevent water loss. Use the same tooth shape as this before anchoring bricks or hanging bricks. The wooden mold bricks are fastened and plastic is driven into them. After the tooth marks are formed, the anchor bricks are embedded and fastened.
However, the formwork should be removed as soon as possible after plastic construction to allow the moisture to escape. When trimming, gently tap the plastic around the end face of the anchor brick with a wooden hammer or hammer head to make it fit tightly. Trimming includes shaving, punching ventilation holes or cutting expansion joints.
During construction, refractory plastics must not come into contact with water; when constructing castables in contact with refractories plastics, refractory plastics must also be waterproofed; the formwork should be removed as early as possible before the oven to allow the masonry to dry naturally.
Due to the "zero-expansion" design of refractory plastics, the cracks and expansion areas of the masonry after drying and oven are filled with refractory fibers to prevent the furnace lining from catching fire and smoking at low temperatures. The cracks and expansion joints will close at around 1350°C.
