Ceramic fiber crucible tube is a lightweight, high-temperature resistant tubular thermal insulation product. Made of high-purity alumina / aluminum silicate fiber by vacuum suction forming, it combines the loading function of a crucible and the thermal insulation advantage of fiber tubes. It is widely used in high-temperature melting, sintering and heat treatment applications.

I. Core Features

High temperature resistance: Continuous service at 1200–1400℃, short-term up to 1700℃; thermal shock resistant, resistant to cracking under rapid temperature changes. Superior thermal insulation: Thermal conductivity of only 0.06–0.18 W/(m·K), low heat storage, remarkable energy saving effect. Light weight and low shrinkage: Bulk density 280–450 kg/m³, linear shrinkage at high temperature ＜3%, no powder shedding and no cracking. Chemical stability: Acid and alkali resistant, resistant to molten metal erosion, inert to most high-temperature media. Easy machining: Can be cut, drilled and slotted to fit non-standard sizes.

II. Common Materials and Temperature Grades

Standard (STD): Aluminum silicate fiber, continuous 1100℃, maximum 1260℃. High Alumina (HA): Al₂O₃ ≥60%, continuous 1250℃, maximum 1350℃. High Purity (HZ): Al₂O₃ ≥70%, continuous 1350℃, maximum 1430℃. Alumina Fiber Type: Al₂O₃ ≥95%, continuous 1500℃, short-term 1700℃.

III. Typical Applications

Investment casting: Vacuum / medium-frequency melting furnaces, crucibles and casting sleeves for precious metals (gold, silver, platinum). Industrial furnaces: Furnace tubes, thermocouple protection tubes and heating element sheaths for tube furnaces, muffle furnaces and pusher kilns. Heat treatment: Insulation linings and supporting tubes for high-temperature sintering, annealing and quenching. Metallurgy / Glass: High-temperature gas transmission, molten metal diversion, bushings for glass drawing crucibles.

IV. Specifications and Selection Guidelines

Dimensions: Inner diameter 24–88 mm, length 200–300 mm, wall thickness 5–15 mm, custom sizes available. Selection: Choose material based on maximum working temperature; select purity according to medium corrosion; confirm dimensions based on installation space. Installation: Avoid heavy impact, handle with care; expansion clearance is recommended for high-temperature service.

V. Advantage Comparison (vs Corundum / Graphite Crucibles)

vs Corundum crucibles: Lighter weight, better thermal shock resistance, lower cost; slightly lower strength, not suitable for long-term load bearing. vs Graphite crucibles: Oxidation resistant, non-wetting to metals, better thermal insulation; not suitable for ultra-high temperature (>1700℃), vulnerable to strong alkali corrosion.