Description: Keraplas is a range of phosphate bonded Chrome alumina plastic materials. Compared to conventional phosphate bonded chrome-aluminas, the Keraplas range has appreciably lower shrinkage, which results in superior structural integrity. Applications: 1. Induction furnace repairs 2. Metal splash shields 3. Abrasion resistant linings. 4. Sliding gate maintenance.
Grades: "Patching" A fine (95% - 1mm) Highly plastic material for patching by hand, metal splash protection and abrasion resistant linings. "Capping" A coarse but highly plastic material for induction furnace capping. (95% - 8mm). "Ramming" or "Ladle" A dryish yet plastic ramming material for ladles, pouring boxes and sliding gate nozzles. (95% - 8mm) Composition: The aggregate is tabular alumina: a high purity synthetic alpha alumina polycrystalline aggregate with good thermal shock resistance and excellent bonding properties. The matrix is alumina and chrome oxide, which sinter in a solid state reaction which results in ruby solid solution with negligible volume change. The binder is largely aluminium ortho-phosphate solution, which develops high strength at 100ºC. A complex series of dehydration reactions follow, culminating in a very strong anhydrous bond at 400ºC. The ceramic bond develops from 1000ºC, and rapidly above 1200ºC. Before the phosphate becomes pyroplastic, the chrome - alumina bond is well developed. Consequently Keraplas has very high strength over the whole temperature range from 200ºC to 1800ºC. Chrome oxide also imparts non-wetting properties.
Metal Protection: A sheet of expanded metal, heavy duty, such as Mentex 72, is bent and tacked onto the steel substrate such that it is positioned 10 to 15mm above the surface. Keraplas patching is then pressed into this continuous anchorage and hammered tight. The thickness is typically 25mm. This system is used in the following applications:
- The outsides of steel shells or structures which sometimes come into contact with pouring steel or ferroalloys. Eg.: Launder casings, especially upper edges. AOD hoods. Ladles with hoods. Bases of steel structures especially where silicon spillage is possible. Spincaster cover ends.
- Where occasional metal flow is expected yet there is insufficient space to apply conventional refractories: Eg.: Tundish overflows. Continuous caster emergency launders. Teapot ladle spouts. Handheld purging lances.
- Abrasion resistant linings where geometry is too complex for tiles. Eg.: nozzles.
- Abrasion resistant linings where the temperature fluctuation destroys tiles, Eg.: burner quarls, coke discharge chutes. See also: Keramor chrome alumina mortars Refractory paint, green.