Abrasion Resistant Material

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 hard particles, 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 E is a ready mixed air setting paste painted on. It shows no wear for about 2 months, then it is removed rapidly. Used on fan blades etc. where weight is a problem.

Kerabrade C is vibration castable, requiring intensive mixing.

Kerapatch Stainless is a very hard material, applied in plastic form, for use between 400°C and 1700°C.

Kerabrade 60 is a putty-like plastic material, requiring intensive mixing. It is usually applied in a supporting structure of hexmetal.

Kerasic is a pourable ceramic used for intricate parts which are precast and pre-fired.

Keralcast is a self-levelling material.

Phospatch is a tough material used where chemical corrosion is also present.

Kerabrade D 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.

Kerabrade E

An abrasion resistant plaster/paint. Used where the weight of added material would be a problem, for example on fans. Can be used from 100°C to 900°C. The aggregate is silicon carbide. It forms an extremely hard skin. Just paint it onto steel.

No wear for 2 months, then it is very rapidly destroyed.

Do not use with Flattex.

Supplied wet in buckets, ready to use.

Development no: 49013

Kerabrade C

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

 

Chemical analysis:

Al2O3 46.0%
FE2O3 0.9%
SiO2 49.0%

 

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.

Packing: 25kg plastic bags

Kerapatch Stainless

Description: Kerapatch stainless is a phosphate bonded chrome-alumina plastic material. Compared to conventional phosphate bonded chrome-alumina, Kerapatch stainless has appreciably lower shrinkage, which results in superior structural integrity. It is supplied in soft plastic consistency, ready to use, in plastic buckets.

Applications:

  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.

Chemical analysis:

Al2 O3 82.0%
Cr O 7.2%
Fe2 O3 1.7%
SiO2 4.0%
TiO2 0.02%
CaO 1.5%
MgO 0.2%
Na2 O 0.3%
K2 O 1.0%
P2 O5 3.4%
Total 101.5%

 

Packaging: 25kg plastic buckets, ready to install.

See also: Keramor chrome alumina mortars Refractory paint, green. Keraplas; Similar material with green chromic oxide. Alumina castables; Keratab and Rubycast. Injectable Rubyject.

Kerabrade 60

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.

Density: 2,5g.cm³

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.

Chemical Analysis:

Al2 O3 54.0%
Fe2 O3 0.6%
SiO2 44.0%

 

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.

Kerasic

Description: Kerasic is alumina bonded silicon carbide. The main problem with silicon carbide is that it oxidizes 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

Chemical analysis:

Al2 O3 34.0
SiO2 2.0%
SiC 58.0%
CaO 6.0%

 

Packaging: 25kg plastic bags.

Water addition for pouring: +12%

Vibration casting: +9%

Keralcast

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 1750C 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.

Phospatch

A patching material for hot surfaces and surfaces difficult to bond to. Phospatch is virtually impervious. It is totally silica free and immune to thermite reactions. It is very sticky and sets in 10 minutes.

Chemical analysis:

Al2O3 88%
CaO 4,5%
P2O5 7%

 

Maximum service temperature: 1780°C

Density: 2,6g/cm3

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 thermite 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

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 dry out 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%
Fe2O3 1.6%
SiO2 10%
CaO 7%
MgO 0.5%
Na2O 0.2%
K2O 0.1%

 

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.