HVOF Tungsten Carbide
A&A Coatings material exhibits the best low temperature abrasive wear resistance of
any HVOF coating. The HVOF Tungsten Carbide coatings are typically denser, better
bonded, exhibit a higher thickness limit and show a superior abrasive wear resistance
than Plasma Sprayed tungsten carbide-cobalt coatings. This material is recommended for
applications in which abrasive wear is the primary failure mechanism.
Material Powder Characteristics
| Typical Composition: | Cobalt 12% Tungsten Carbide Balance NOTE: A&A can provide Tungsten Carbide coatings of many different compositions. Please inquire for more information. |
Physical Properties of Coating
| Surface Texture As-Sprayed (microinches aa): |
170 – 250 |
| Ground – 400 grit diamond (microinches aa): |
28-36 |
| Lapped (microinches aa): | 1-3 |
| Coating Macrohardness: | Rc60 |
| Coating Weight (lb/ft2/.001″): | .076 |
| Bond Strength on Low Carbon Steel Substrate (PSI): |
>12,000 |
Thickness Limitation
A&A Coatings HVOF Sprayed Tungsten Carbide was designed for use in thin coatings,
not more than .5mm (.025″) thick. If sprayed thicker, the probability of cracking and
delamination will increase rapidly, as is the case of thick coatings of all fine powders.
Surface Preparation
A&A Coatings HVOF Sprayed Tungsten Carbide is self-bonding to mild steel and to
titanium which has been cleaned to remove surface oxides. This cleaning is accomplished
with a light grit blast. Preheating of titanium should be done with care, to prevent
reformation of surface oxides.
Finishing
In finishing, use standard precision grinding equipment and flood with coolant of water
plus 2% soluble oil. The following procedures have produced high finishes:
1. Rough grinding with 150 grit diamond wheels.
2. Finish grinding with 400 grit diamond wheels.
3. Wheel speeds: 1525-1830 m/min (5000-6000 SFPM)
Infeed per pass: .013 mm max. (.0005″)
Work speed:
Cylindrical – 120 m/min (400 SFPM)
Flat – Table speed 12 m/min (40 SFPM)
Cross feed:
Flat — 1.3 mm (.050″) per pass, roughing
0.5 mm (.020″) per pass, finishing
Traverse:
Cylindrical — 2.0 mm (.080″) per revolution, roughing
1.0 mm (.040″) per revolution, finishing.