Claims
- 1. A method of protecting the surface of a powder metal artefact which comprises applying thereto a coating composition comprising an aqueous dispersion containing zinc particles and as bonding agent for the composition a mixture of sodium silicate or potassium silicate with sufficient lithium polysilicate to achieve a cured coating which is highly adhesive and is resistant to effects of moisture at temperatures considerably above ambient.
- 2. A method according to claim 1, wherein the weight ratio of lithium polysilicates to sodium or potassium silicate is from 1:2 to 2:1.
- 3. A method according to claim 1, wherein the weight ratio of lithium polysilicate to sodium silicate is 1:1.
- 4. A method according to claim 1, at least 35% by weight of the zinc present is in the form of zinc flake.
- 5. A method according to any one of the preceding claims wherein a vacuum is applied to the artefact prior to or during application of the coating composition.
- 6. A modification of the method of any of the preceding claims wherein the mixture of sodium and/or potassium silicate and lithium polysilicate may be replaced by an alkyl silicate binder.
- 7. An aqueous coating composition comprising zinc flake and as bonding agent for the composition a mixture of sodium silicate or potassium silicate with sufficient lithium polysilicate to achieve a cured coating which is highly adhesive and is resistant to effects of moisture at temperatures considerably above ambient.
- 8. A non-foaming aqueous coating composition comprising a mixture of sodium silicate or potassium silicate with sufficient lithium polysilicate to achieve a cured coating which is highly adhesive and is resistant to effects of moisture at temperatures considerably above ambient, lithium hydroxide and a surfactant.
- 9. A non-foaming aqueous coating composition according to claim 8 which comprises from 10 to 50% lithium polysilicate, from 25 to 50% sodium or potassium silicate, from 10 to 25% lithium hydroxide, from 1 to 2% of a surfactant and from 1 to 2% of an anti-foaming agent.
- 10. A method of coating a non-passivated galvanized artefact which comprises applying a non-foaming aqueous coating composition comprising a mixture of sodium silicate or potassium silicate with sufficient lithium polysilicate to achieve a cured coating which is highly adhesive and is resistant to effects of moisture at temperatures considerably above ambient, lithium hydroxide and a surfactant to said artefact and then curing the artefact at a temperature of from 250 to 350° F.
- 11. A powdered metal artefact having a surface coating which comprises zinc particles and a mixture of sodium or potassium silicate and lithium polysilicate.
- 12. An alkyl silicate coating composition comprising 100 parts by weight of a silicate solution containing 20 to 25% by weight alkyl silicate, 50 parts by weight zinc flake, 50 parts by weight zinc dust and 2 parts by weight of a wetting and dispersing agent.
Parent Case Info
[0001] This application claims priority from U.S. provisional application Serial No. 60/285191 filed on Apr. 20, 2001.
Provisional Applications (1)
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Number |
Date |
Country |
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60285191 |
Apr 2001 |
US |