Abrasion resistant materials are difficult to select. "Abrasion" covers a wide range of conditions from impact by rocks to wear by fine particles in an air stream. All abrasion resistant materials have hardparticles, the "aggregate", set in a strong "matrix". Usually the matrix wears down until it releases the aggregate particles. Consequently the surface acquires a rough texture. Some materials,such as Kerabrade C and Kerabrade 60 are designed to give a smooth, low friction surface
Kerabrade A is self leveling and self de-airing and requires no vibration. Developed for quick setting ultra thin perimeter walls.
Kerabrade C is vibration castable, requiring intensive mixing.
Kerasic is a self-levelling material.
Kerabrade 60 is a putty-like plastic material, requiring intensive mixing. It is usually applied in a supporting structure of hexmetal.
Kerabrade T is a slip cast reconstituted alumina tile material, which can perform quite well after firing to 1200°C. It suffers from the disadvantage of being very abrasive towards your mixing equipment.
Kerapatch Stainless is a very hard material, applied in plastic form, for use between 400°C and 1700°C.
Phospatch is a tough material used where chemical corrosion is also present.
Keralcast Alumina based abrasion resistant castable.
Saffex An extremely hard and strong cementitious material. Suitable for floor tiles etc.
Description: An abrasion resistant high strength castable for use up to 1200°C. The matrix is very hard, and fracture will occur right through the aggregate grains.
Physical properties: Bulk density: 2,25g/cm³
Cold crushing strength: 100 to 150MPa
Permanent linear change: -0,2% after 800°C
Thermal conductivity: 1,6W/mK
Installation: Place +7,5% water in a planetary (bakery type) mixer. Add half of the powder and mix until fluid. Add another quarter of the powder and mix until fluid. Slowly add the last quarter of powder, keeping the mix fluid. This will take about 5 minutes. The result is a self-levelling fluid.
25kg plastic bags
Description Kerapatch stainless is a phosphate
bonded chrome-alumina plastic material. Compared to conventional phosphate bonded chrome-aluminas, Kerpatch stainless has appreciably lower shrinkage, which results in superior structural integrity. It is supplied in soft plastic consistency, ready to use, in plastic buckets.
1. Induction furnace repairs.
2. Metal splash shields.
3. Abrasion resistant linings.
4. Sliding gate maintenance.
5. Long-life ladles and teapot ladles.
6. Runners and launders.
7. Water-cooled plate protection.
Composition: The aggregate is fused chrome alumina: a high purity synthetic alpha alumina polycrystalline aggregate with good temperature and chemical stability. The matrix is tabular alumina which has good bonding properties and thermal shock resistance. The phosphate binder 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 it has very high strength over the whole temperature range from 100ºC to 1800ºC.
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. The material is then pressed into this continuous anchorage and hammered tight. The thickness is typically 25mm. This system is used in the following applications:
1. 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.
2. 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.
3. Abrasion resistant linings where geometry is too complex for tiles. eg.: nozzles. 4. Abrasion resistant linings where the temperature fluctuation destroys tiles, Eg.: burner quarls, coke discharge chutes.
Where mechanical stresses are great, another system is used; Hexmetal reinforcing. The sheet of honeycomb metal is welded onto stainless steel plate and the keraplas packed into it. Each cell of the honeycomb is independently anchored, and the structure can withstand severe expansion and contraction and mechanical abuse. This system can be used on water-cooled copper panels etc.
Packaging; 25kg plastic buckets, ready to intstall.
See also: Keramor chrome alumina mortars Refractory paint, green. Keraplas; Similar material with green chromic oxide. Alumina castables; Keratab and Rubycast. Injectable Rubyject.
Description; An abrasion resistant refractory installed in plastic form. used between 200ºC and 1000ºC. The matrix is hard and does not wear much faster than the aggregate.
Cold Crushing Strength; 120 to 180 MPa (after 800ºC)
Thermal conductivity; 1.8W/mK
Permanent linear change after 800ºC; -0.35%
Maximum particle size; 5mm.
Installation; Mix the powder in high shear mixer, preferably a bakery type planetary mixer for 1 minute. The add +5.3 to +5.8% water and mix for about 5 minutes. it will reach a plastic consistency suitable for hand packing. Normally it is placed into hexmetal reinforcing.
Packaging; 25kg plastic bags.
Description; Kerasic is alumina bonded silicon carbide. The main problem with silicon carbide is that it oxidises to silica. The alumina bond reacts with the silica to form a mineral called mullite, which has a needle like structure and imparts high strength, and has a melting point of 1850ºC. Kerasic is not as electrically conductive as other silicon carbide materials. Kerasic is a very fine grained material which can be poured like thick cream. Very detailed castings can be made with wall thicknesses down to 2mm. Plates have been made 300mm x 300mm x 5mm thick. The surface texture is very smooth, and the abrasion resistance of fired parts is excellent. The strength increases with repeated firing.
Cold crushing strength; 50 - 120 MPa
Al2 O3 34.0%
Packaging; 25kg plastic bags.
Water addition for pouring; +12% vibration casting; +9%
Keracast 6 is a totally cement free, CaO free material. It is consequently highly refractory. The chemical analysis is approximately as follows;
The mineral composition is about 87% alpha alumina, which is synthetic corundum, with a melting point of 2013ºC and 13% mullite, Al2O3 .SiO2 , with a melting point of 1850ºC. The material therefore contains very little liquid phase below 1850ºC. Both mullite and corundum are chemically inert and immune to attack by sulphurous or acid gases. To develop good strength we pre-fire the castings to 1200ºC, so that the silica is all present in the mineral mullite. Mullite grows in needle-like crystals, which enhance the strength of the composite. Corundum is the second hardest natural mineral, with a hardness of 9 on the Moh scale. (Diamond is the hardest, at 10 on the scale.) The only refractory materials with higher melting points are lime, magnesia and zirconia. All three are prone to thermal shock damage.
Mix with + 10% Super Binder L and vibration cast.
Packaging; 22,5kg powder and 2,5kg liquid Super Binder L.
Formulation no. 11484
Formulation no. 32031 is an upgrade with 94,5% Al 2O 3 and 4.4% SiO2.
Vibration cast with +11% Super binder L
Formulation no. 32035 is 93% Al₂O₃ and 6% SiO₂ Use +15% Super Binder L. Flows by tapping. % minutes working time.
Note that all of these are very high strength and difficult to break out.
Claimer; The above information had better be correct, since Dave Onderstall rests his reputation on it.
A patching material for hot surfaces and surfaces difficult to bond to. Phospatch is virtually impervious. It is totally silica free and immune to thermit reactions. It is very sticky and sets in 10 minutes.
Chemical analysis; Al2O3 88%
Maximum service temperature; 1780°C
Max. particle size; 3mm
Mechanical properties; Phospatch has an exothermic setting reaction and expands slightly while setting. It sets in 10 minutes, and grips onto nearly all surfaces, even copper. Phospatch is not brittle; a hammer blow will make a slight dent rather than shatter it. Test cubes on cold crushing strength deform without breaking. The impervious structure gives immunity to chemical attack except on the surface. Strength increases with temperature, but the malleability changes to a more brittle rigid ceramic structure.
APPLICATIONS; Protection of waffle coolers from molten metal contact.
Patching of launders, flues, any hot repairs of furnaces.
Patching of surface contact line in aluminium furnaces to prevent thermit reaction.
Colour; Pure white.
Mixing; Mix 100 weight parts powder to 22 weight parts liquid gives a gives a good workability, but can be used from pourable to rammable without any problem. A lot of gas is evolved during mixing. Do not make large batches, as the exothermic reaction is self accelerating. Setting can be retarded by refrigerating the liquid binder.
Patches and castings can be heated up 20 minutes after mixing.
Packaging; 5kg box repair kit, with mixing bowl and gloves.
10kg combined weight packs.
25kg packs, combined weight of powder and liquid.
25kg plastic bags of powder and 45kg polycans of liquid.
Shelf life; 3 years.
Development no. 39107
Claimer; This information had better be correct, because Dave Onderstall stakes his reputation on it.
Kerabrade D is a bauxite based abrasion resistant material. It is expensive and requires very intensive mixing in a planetary(bakery type) mixer. It is a high silica fume vibration castable. It is used mainly for precast shapes, since the dryout is difficult due to the very low porosity and permeability.
Maximum service temperature; 1200°C
Maximum particle size; 3mm
Bulk density after 110°C; 2,75g/cm³
Thermal conductivity at 800°C; 2,0W/mK
Cold Crushing Strength dried 110°C; 130MPa. (Rings like steel)
Chemical analysis; Al₂O₃ 78%
Mixing; Add +6% to +7% water and mix for 12 minutes in a planetary mixer. Initially the material will appear bone dry. Puddling technique may be used. Any deviation or short cuts will not achieve high strength. Setting time is 2 to 6 hours.
Drying is very tricky, over 5 days for large castings. Let us do it.
Packaging; 25kg polyethylene bags.
Shelf life; Dodgy, better to use within 2 weeks.
Development no. 72303
Claimer; This data had better be correct, since Dave Onderstall rests his reputation on it.
Probably the first ever abrasion resistant insulation material. It is an aluminosilicate material containing hollow ceramic balls called cenospheres. The matrix is extremely fine, cohesive and dense, but the bulk of the volume is sealed air bubbles.
The density is 1,7kg/l
The cold crushing strength climbs to around 50 MPa at 400 C and drops back to 25 to 30 MPa at 1250 C
Can be poured with an addition of +16% water, and will flow self-levelling.
Can be plastered with plus 12% water.
A variant is Archiecoat which can be plastered with +16% water and painted about 3mm thick with an addition of +20% water.
Protection of steel exposed to heat; Ducting and shells of dust collectors etc. Can be trowelled onto expanded metal.
Development no. 94412
25kg plastic bags.
Shelf life ;
An extremely hard and strong cementitious material. Suitable for floor tiles etc.
Chemistry; 70% silica,
20% Ciment fondu
The maximum particle size is 0.3mm, so fillers can be added.
Add +9,7% water and mix very intensively for about 7 minutes, until it flows.
The density is about 2,5.
The price is R8/kg + VAT
Further work is needed on deflocculation and setting speed.
Development no. 115201
Description: Alumina based abrasion resistant castable.
This is new technology, previous high abrasion resistant ceramics are based on high additions of silica fume. Keralcast has only 1% silica and can therefore be used at high temperatures, up to 1750ºC with virtually no molten phase present.
Density: 3.06 g/cm³
Max particle size: 5mm
Thermal conductivity: 2W/mK
Water addition: Extremely low: +4.5%
Mixing: 7 minutes in a bakery mixer or 20 minutes in a pan mixer.
The consistency can be adjusted from putty to self-flowing, as preferred.
The setting time can be adjusted from half an hour to 6 hours, as preferred.
Testing: Try to grind it on a bench grinder.
Shelf life: 2 years.
Packaging: 25 kg plastic bags.
Project no. 1142
Claimer: This data sheet had better be correct because Dave Onderstall stakes his reputation on it.
A very high strength SCC (self compacting concrete). It differs from Dump Mixes in that it can be carried in buckets, but direct discharge into moulds or shuttering is preferred.
Kerabrade A is self leveling and self de-airing and requires no vibration. It is derived from Perimeter 1 which was developed for quick setting ultra thin perimeter walls;
It develops 136 MPa in 4 days. Not for use at high temperatures. It is volume stable.
Wear; It should wear to a smooth surface, because the matrix is as hard as the aggregate. (Most abrasion resistant materials become rough as the aggregate protrudes.) Kerabrade A is therefore ideal for ore chutes and sliding applications.
Maximum particle size is 7mm.
Mixing; 3 bags plus one polycan.
78 weight parts powder to 22 weight parts liquid binder.
100:28 or +28% liquid binder.
Flow time; 20 minutes.
Strip time; 3 hours
Packaging; 3 x 26kg bags plus 1x 22kg polycan of liquid binder for every 100kg.
Shelf life: 1 year.
Development No: 151568
Claimer; This provisional data sheet is incomplete. Kerabrade A is a new product and more data will be added as it becomes available.
An abrasion resistant material
Maximum service temperature; 1250°C
Cold crushing strength; air dry: 100 MPa 110°C: 120 MPa 1000°C: 150MPa. (+8%H₂O)
Applications: Sliding or impact abrasion resistance, wet or dry. See detailed instructions below.
Mixing: Add +8% water by puddling in a bakery mixer, 10kg batches, read instructions below.
Packaging: 10kg plastic bags
Development no. 85765
Kerabrade S is installed usually 15mm thick onto a steel shell to delay wear of the shell. To optimize adhesion to the shell, the plaster is anchored to expanded metal. The preferred grade of expanded metal is Mentex 72. The expanded metal may be raised slightly off the shell. To do this the expanded metal is bent outwards at the desired intervals for welding. To bend it, cut a short (about 9mm) piece of pipe of diameter approximately 55mm. Weld this to a rod about 800mm long. Place the expanded metal on a concrete slab. Slide the pipe under the expanded metal to the point to be bent out. Strike the expanded metal sharply with a hammer until it reaches the concrete. This results in bumps raised about 5mm, which can now be welded to the shell.