Magfine Corporation

Magnet coating characteristics comparative test

Magfine Corporation is the best magnet company with 25 years in business

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) Corrosion resistant salt spray (Hr) Porosity Demagnetization rate Abstract 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

Element symbol Name of element φ10mm×10mm Properties Usage
Trivalent chromium zinc
3CrZn Chromate treatment. Recently hexavalent chromium has been regulated as an environmentally destructive substance and replaced with trivalent chromium
  • Eletronic parts,
  • Industrial tool parts
Ag Silver Ag Silver has the best electric conductivity out of all the metals, low contact resistance and good solderability but is easy to discolor.
  • Electronic parts
  • connectors
  • eating utensils
  • accessories
Au Gold Au Gold has good corrosion and oxidation resistance along with low electrical resistance.
  • Electronic parts
  • Electrical contact parts
  • Decorations
  • Accessories
Cr Chrome Cr Chrome has good abrasion and oxidation resistance and will not lose its shine in the atmosphere.
  • Exterior parts
  • Medical supplies
  • Audio-visual equipment
  • Accessories
Cu Copper Cu Copper is easy to discolor so is used as a base. It is used to fill in dents and bring out a shine.
  • Casting products
  • ABS resin base
  • Traditional colored decorations
Ni Nickel Ni Nickel is chemically stable and has good anti-rust properties.
It can be used for a wide range of purposes and is used as a base for gold plating, chrome plating etc. It can cause skin irritation.
  • Ectronic parts,
  • Connectors
  • Base platings
  • Accessories
NiBlack Black nickel NiBlack Black nickel is an alloy plating made of nickel, zinc and sulphur. The color may vary depending on the type of plating used as a base.
  • Decorations
  • Accessories
Sn Tin Sn Tin has excellent anti-corrosion properties and does not oxidize easily. It does not lose its shine easily and is safe to use in foods.
  • Eating utensils
  • Cans
  • Tin objects
  • Decorations
  • Accessories
Rh Rhodium Rh Rhodium has excellent anti-corrosion properties and does not oxidize easily. It does not lose its shine easily and is safe to use in foods.
  • Electronic parts,
  • Electrical contact parts
  • Audio parts
  • Decorations
  • Accessories
- Un-treated no-coating No surface treatment coating. Rust will develop easily on neodymium magnets.  

Anti-rust properties test

  Magfine Company S Other companies Magfine Company T Magfine
Duration HDCcoating epoxy
Normal epoxy Anti-rust undercoat Zn for automobiles HDC coating
polyimide MF305
Normal epoxy

3 layer nickel

Before start of test 初期状態
After 72 hrs 72時間
After 312 hrs 312時間
After 504 hrs 504時間

Neutral salt spray test 5% sodium chloride solution test temperature 35℃ JIS Z2371

Comparison chart of surface treatment

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

To buy any products or ask any questions, please visit our online store or contact the corresponding department.
111-10 Moniwa-aza-hitokita-nishi, Taihaku-ku, Sendai-shi, Miyagi 982-0251 TEL +81 22-281-3956 FAX +81 22-281-3967

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