Comparison of Coating Performance
Below is a comparison of the performance of various coating materials used on neodymium magnets. It is important to take into consideration the usage environment when choosing the coating as the properties of the magnet will change depending on the type of coating.
| Material | Code | Thickness (μm) | Salt Spray (Hr) | Porosity | Demagnetization Rate |
Colors | PCT (Hr) |
|---|---|---|---|---|---|---|---|
| Hi-Den Coat MF304 Epoxy | MF304 Epoxy | 5-100 | >500 | - | - | Multi-colors | >100 |
| MF305 Polyimide | MF305 Polyimide | 5-50 | >400 | - | - | Multi-colors | >100 |
| Zinc | Zn | 10-15 | >24 | <0.1 | <0.2% | White | >16 |
| Coloured zinc | Colour-Zn | 10-15 | 72 | <0.1 | <0.1% | Multi-colors | >24 |
| Nickel | Ni | 10-20 | 4 | <0.5 | <0.3% | Silver | >16 |
| Double nickel | Double-Ni | 15-20 | 24 | <0.2 | <0.3% | Silver | >16 |
| Nickel-copper-nickel | Ni-Cu-Ni | 15-30 | >48 | <0.1 | <0.1% | Silver | >42 |
| Zinc-nickel-alloy | Zn-Ni Alloy | 10-20 | >720 | <0.1 | <0.1% | Multi-colors | >72 |
| Other company's Epoxy | EPOXY | 10-50 | >300 | - | - | Black | >24 |
| Electroless Nickel | Electroless Ni | <1 | >72 | - | - | Silver | >24 |
Types of plating for magnets
Anti-rust properties test
Neutral salt spray test 5% sodium chloride solution test temperature 35℃ JIS Z2371
Comparison chart of surface treatment
| Process / Criteria | Electric plating | Thermal spraying | Deposition | Electrodeposition | Parylene coating | Hi-DEN COAT |
|---|---|---|---|---|---|---|
| Process | Wet | Dry | Dry | Wet | Dry | Dry |
| Selection of object to be coated | Large objects are difficult | Large objects are difficult | No problem | Small objects are difficult | Large objects are difficult | No restrictions |
| Deposition speed | Slow | Fast | Slow(limited) | Fast | Slow | Slow |
| Deposition adhesion | Strong | Strong | Weak | Strong | Weak | Strong |
| Hydrogen embrittlement | Potential risk | None | None | Potential risk | None | None |
| Effect on environment | Very large | Small | Small | Small | Small | Small |
| Adherend strength | Weak | Very weak | Weak | Strong | Weak | Strong |
| Choice of color | Only metal colors | None | Only metal colors | Fairly large | None | Fairly large |
| Insulation | Only certain materials | Only certain materials | Only certain materials | Yes | Yes | Yes |
| Machining after processing | Not possible | Not possible | Not possible | - | Not possible | Possible |
| Productivity | Good | Difficult | Difficult | Good | Good | Good |
| Addition of modifying material (Specific to properties of various types) |
Not possible | Not possible | Not possible | Not possible | Not possible | Possible |
