Stock Material: MoB-CoCr Powder, Agglomerated and Sintered
| Nominal composition | wt.% |
| Molybdenum Boride | base |
| Total boron | 8.0-8.5 |
| Cobalt | 25-28 |
| Chrome | 13.5-15 |
Molybdenum Boride Coating Properties
| Feature | S.I. Units | U.S. Units |
| Apparent metallographic porosity | <1.5% | |
| Bond strength to carbon steel | 70 MPa @ 500 microns | 10,000 PSI @0.020″ |
| Hardness | 1000-1200 HV300 | |
| Typical as-sprayed roughness Ra: | 2-3.2 µm | 90-130 μin |
| Maximum coating thickness | 750 microns | 0.030” |
| Maximum working temperature | 900°C | 1,650°F |
A Micrograph of an Anti-Stick HVAF Molybdenum Boride Coating
Molybdenum Boride Coating Characterization
The Molybdenum Boride coating has good resistance to high temperature erosion and sliding wear.
Thermal shock resistance is fair.
General corrosion and high temperature corrosion resistance are very good.
The HVAF MoB coating has excellent non-stick properties.
The coating is inert to molten metals (zinc, aluminum, etc.).
Typical Applications
Sliding wear and erosion at high temperatures, specifically for works related to oil well drilling;
non-stick coatings for a molten metals service (die-casting parts, galvanizing bath parts, sink rolls, etc.).
Non-stick Coatings for Hot Dipping Rolls
MoB/CoCr cermet material with high durability in molten alloys has been developed for aluminum die-casting parts, and for hot continuous dipping rolls in Zn and Al-Zn plating lines, [Mizuno and Kitamura, 2007]. The tests revealed that a MoB/CoCr coating has high durability without dissolution in the molten Al-45wt.%Zn alloy. Using an undercoat is effective in reducing the effect of large differences in thermal expansion between the MoB/CoCr topcoat and substrate of stainless steel AISI 316L, widely used for hot continuous dipping.
MoB-based cermet powders (MoB/NiCr and MoB/CoCr) were deposited on SKD61 (AISI H-13) substrates used as a preferred die (mold) material [Khan et al 2011]. The durability of these coatings on cylindrical specimens against soldering has also been investigated by immersing them in molten aluminum alloy (ADC-12) for 25 hours at 670 °C.
The Kermetico HVAF C7 Gun Spraying a MoB-CoCr Non-Stick Coating
Kermetico HVAF Equipment to Spray Composite MoB Coatings
Most Kermetico guns can spray molybdenum boride composite powders.
- Convertible HVOF and HVAF equipment:
- Multi-purpose HVAF AK systems, with a range of spray guns:
- AK7 – a high-power gun for the thermal spray of large parts, maximum MoB spray rate – 16 kg (35.5 lbs.)/hour
- AK6 – a universal gun to spray a balanced mix of parts in a job shop, maximum MoB spray rate – 14 kg (31 lbs.)/hour
- AK5 – a compact gun to spray smaller parts, thin walls and complex surfaces, maximum MoB spray rate – 8 kg (18 lbs.)/hour
- AK-ID – an 80 mm (3.15”) and larger internal diameter spray gun, maximum MoB spray rate – 8 kg (18 lbs.)/hour
- AK-IDR – a rotating ID gun to spray 4” (100 mm) and larger bores, maximum MoB spray rate – 8 kg (18 lbs.)/hour
- AK-HH – a handheld gun for on-site coating, Maximum MoB spray rate – 8 kg (18 lbs.)/hour.
- Additional equipment:
- An HVAF grit feeder for the grit blast preparation of parts to reduce coating costs
- A Gas Permeability Tester for an instant check of a coating’s through porosity
Kermetico Inc. –Material Science Excellence, HVAF and HVOF Equipment Manufacturing and Thermal Spray Coating Services Since 2006
We create equipment that helps materials scientists, engineers, and businessman achieve their goals.
We have installed more than 60 HVAF and HVOF systems in the USA, Europe, Japan and China.
Some of the systems are installed in Universities and National Labs, but most of them work in production thermal spray shops.
We proudly design and produce our coatings and our HVAF & HVOF thermal spray equipment in California and install it all over the world.
You can visit our R&D center in Benicia to meet our designers and see our HVOF & HVAF equipment in action.
We provide HVAF and HVOF thermal spray coating services to our customers in California, USA.
Literature
- Khan F. F., G. Bae, K. Kang, H. Na, J. Kim, T. Jeong, and C. Lee, (2011) Evaluation of DieSoldering and Erosion Resistance of High Velocity Oxy-Fuel Sprayed MoB-Based Cermet Coatings, Journal of Thermal Spray Technology 20(5) 1022-1034
- Mizuno H. and Junya Kitamura, (2007) MoB/CoCr Cermet Coatings by HVOF Spraying against Erosion by Molten Al-Zn Alloy, Journal of Thermal Spray Technology 16(3) 404-413
