The difference between lightweight refractory materials and thermal insulation materials

The difference between lightweight refractory materials and thermal insulation materials

Raw material composition

1. Lightweight refractory materials: mostly based on refractory clay, high-alumina bauxite, siliceous raw materials, etc., with appropriate amounts of foaming agents, binders and other additives. For example, lightweight high-alumina bricks use high-alumina bauxite clinker as aggregate, introduce substances that can decompose and produce gas at high temperatures, and form a porous structure after firing. These raw materials themselves are rich in high-temperature resistant oxide components, which ensure the refractory properties of the materials.
2. Thermal insulation materials:The sources of raw materials are wide and diverse. Mineral wool such as rock wool and mineral wool are made of natural rocks (such as basalt, diabase) or metallurgical slag as the main raw materials, which are spun or blown into fibers after high-temperature melting; organic thermal insulation materials such as polystyrene foam boards are made of polystyrene resin and formed through a foaming process. Different raw materials determine the different thermal insulation mechanisms and characteristics of thermal insulation materials.

Microstructure

1. Lightweight refractory materials:The internal microstructure is porous, but the pores are relatively uniform and well connected, so that the gas can diffuse moderately at high temperatures and relieve thermal stress. Its pore walls are generally thicker and composed of high-temperature resistant mineral crystals, which not only ensures a certain strength, but also supports the material to maintain structural stability under high temperature environments and withstand thermal shock.
2. Thermal insulation materials:Microscopically, they are also porous structures, but the pore sizes and shapes vary greatly, and most of them are closed pores. For example, polyurethane foam thermal insulation materials are filled with tiny closed bubbles inside, and air is difficult to flow in these closed spaces, which greatly hinders heat conduction. With this special structure, efficient thermal insulation is achieved, and its pore walls are thin, and the mechanical strength is mainly maintained by the chemical cross-linking structure of the material itself.

Thermal stability

1. Lightweight refractory materials:They have good thermal stability and can withstand frequent temperature changes without cracking or peeling. This is due to their reasonable mineral composition and microstructure. The high-temperature phase and the low-temperature phase can change in coordination when the temperature fluctuates, buffering the stress caused by thermal expansion and contraction. For example, the lightweight refractory materials used in intermittent kilns can still work normally after multiple heating and cooling cycles.
2. Insulation materials:The thermal stability is relatively poor, especially organic insulation materials. When the temperature changes rapidly, the internal structure of the material is easily damaged. For example, in foam plastic insulation materials, sudden temperature changes may cause bubbles to rupture, materials to shrink and deform, and then deteriorate the insulation performance, so it is generally suitable for environments with relatively stable temperatures.

Environmental protection characteristics

1. Lightweight refractory materials:During production and use, dust pollution control is mainly considered. Some products containing special additives may have trace heavy metal volatilization risks, but in general, if advanced processes and environmentally friendly raw materials are used, the environmental impact can be controlled at a low level, and if properly handled after disposal, it can be recycled and reused in some low-requirement scenarios.
2. Insulation materials:Environmental protection issues vary. Energy consumption and dust emissions in the production of mineral wool insulation materials need to be controlled. Inhalation of fiber dust during use is harmful to the human body. Organic insulation materials such as polystyrene foam boards will release toxic and harmful gases during incineration. Their difficult natural degradation also poses challenges to waste disposal. However, new biodegradable organic insulation materials are being developed and promoted.

Cost Price

1. Lightweight refractory materials: Since most of the raw materials are specific refractory mineral raw materials, the processing technology is complex, involving high-temperature firing, fine ingredients and other links, and the cost is relatively high. In particular, some high-quality, high-temperature resistant lightweight refractory materials have large R&D and production costs, and the price has also risen accordingly. They are often used in industrial fields that have strict requirements on production processes and high economic benefits.
2. Insulation materials: The cost span is large. The production cost of mineral wool insulation materials is affected by the price of raw materials and production scale. Large-scale industrial production makes its price competitive. The price of organic insulation materials varies due to different raw materials and foaming processes. Some low-end polystyrene foam boards are cheap, but the research and development costs of high-end and environmentally friendly insulation materials are superimposed, and the price is not low. In general, the insulation materials commonly used in the construction field focus on cost-effectiveness while meeting basic insulation requirements, and the price is more affordable than lightweight refractory materials.