Magnetic recording head having a corrosion-protective layer of a metal salt of a perfluorinated polyether acid
View Patent ↗A process is provided for synthesizing metal salts of perfluorinated polyethers containing at least one carboxylic acid group. The polymeric salts so provided are effective as anti-wetting and corrosion-protective agents. The metal salts of perfluorinated polyether acids may be used to prepare corrosion-protected substrates, including magnetic recording disks and magnetic recording heads.
1. In a magnetic recording head comprised of (a) a substrate of an oxide, nitride or carbide of aluminum, zirconium, silicon or titanium and having (b) an overcoat comprising a film composed primarily of carbon in the essentially amorphous form and having pinholes therein exposing the substrate, wherein the improvement comprises treating the magnetic recording head with a corrosion-protective composition so as to fill the pinholes of the overcoat, the composition containing a corrosion-protective agent comprised of a metal salt of a fluorinated polyether having at least one carboxylic acid group.
2. The magnetic recording head of claim 1 , wherein the fluorinated polyether is a perfluorinated polyether.
3. The magnetic recording head of claim 2 , wherein the perfluorinated polyether has one carboxylic acid end group.
4. The magnetic recording head of claim 3 , wherein the perfluorinated polyether has two carboxylic acid groups.
5. The magnetic recording head of claim 2 , wherein the perfluorinated polyether is comprised of monomer units having the structure —CF 2 —O—, —CF 2 —CF 2 —O—, —CF(CF 3 )—O—, —CF(CF 3 )—CF 2 —O—, or a combination thereof.
6. The magnetic recording head of claim 1 , wherein the fluorinated polyether is a linear polymer.
7. The magnetic recording head of claim 1 , wherein the metal salt is an alkali metal salt.
8. The magnetic recording head of claim 1 , wherein the fluorinated polyether has a number average molecular weight in the range of approximately 500 to 10,000.
9. The magnetic recording head of claim 8 , wherein the fluorinated polyether has a number average molecular weight in the range of approximately 1000 to 5000.
10. The magnetic recording head of claim 9 , wherein the fluorinated polyether has a number average molecular weight in the range of approximately 2500 to 3500.
11. The magnetic recording head of claim 1 , wherein the improvement further comprises coating the carbon overcoat with a lubricating film of a perfluoropolyether prior to deposition of the corrosion-protective composition.