Process for lubricating a surface such as a mould for the manufacture of a glass object

Abstract

Process for lubricating a surface for the manufacture of a glass object, in which a layer of lubricant is periodically deposited on the surface. This layer of lubricant is produced with the aid of a source of heat such as an oxyfuel flame having a temperature higher than 2000° K. through which there is injected during a given period of time a gaseous hydrocarbon or a mixture of gaseous hydrocarbons comprising at least 15% of a constituent in respect of which the ratio .[.fo.]. .Iadd.of .Iaddend.the number .[.oc.]. .Iadd.of .Iaddend.carbon atoms to the number of hydrogen atoms C/H is higher than 0.75. The rate of injection of the hydrocarbon through the flame and the temperature of the latter are controlled in such manner as to obtain a porous layer of carbonaceous particles capable of burning in the air when they are deposited on the glass object when the latter is still hot.

I claim: 
     
       1. A process for providing a lubrication layer on a .[.mold.]. surface .Iadd.of an object which contacts an article.Iaddend., in which the layer of lubricant is periodically deposited onto the surface, the process comprising .[.maintaining the temperature of the surface at least about 500° C. as the lubricant is deposited thereon,.]. producing said layer of lubricant by .[.a.]. .Iadd.an oxygen-fuel superstoichiometric .Iaddend.flame having a temperature higher than 2000° K. .Iadd.and an oxygen factor greater than 1, .Iaddend.and injecting a gaseous hydrocarbon through the flame for a given period of time, the gaseous hydrocarbon comprising at least 15% of a constituent in respect of which the ratio of the number of the carbon atoms to the number of hydrogen atoms C/H is higher than 0.75, the rate of injection of the hydrocarbon through the flame and the temperature of the flame being controlled in such manner as to obtain a porous layer of carbonaceous particles capable of burning in .[.the.]. air when they are .[.deposited on the.]. .Iadd.transferred onto a .Iaddend.surface .Iadd.of the article .Iaddend.when the .[.surface.]. temperature .Iadd.of the article .Iaddend.is equal to at least about 500° C..[., the particles adhering to the surface.].. 
     
     
       2. A process for lubricating a .[.mould.]. .Iadd.surface .Iaddend.according to claim 1, the temperature of the flame being higher than 2500° K. .[.3. A process for lubricating a surface according to claim 1 or 2, the flame comprising an oxygen-fuel superstoechrometric flame having an oxygen 
     
     
        factor higher than 1..]. 4. A process for lubricating a surface according to claim .[.3.]. .Iadd.1.Iaddend., the .[.gaseous hydrocarbon.]. .Iadd.flame .Iaddend.having an oxygen factor of .[.the.]. between 1.1 and 
     
     
        1.4. 5. A process for lubricating a surface according to claim 1, in which the hydrocarbon contains at least 15% of a constituent in respect of which the ratio of the number of carbon atoms to the number of hydrogen atoms 
     
     
        C/H is equal to at least 1. 6. A process for lubricating a surface according to claim 1, in which the hydrocarbon is chosen from the group consisting of acetylene, propyne, .[.propadiene,.]. benzene, acetylene-ethylene mixtures, mixtures constituted by propyne-propadiene-propylene and other C 3  and C 4  hydrocarbons. 
     
     
           A process for lubricating a surface according to claim 1, in which the hydrocarbon is an acetylene-ethylene mixture in a ratio of about 20% acetylene by volume and 80% ethylene by volume, the temperature of the 
     
     
        flame being higher than 2200° K. 8. A process for lubricating a surface according to claim 1, in which successive quantities of the gaseous hydrocarbon are injected through the flame, each said quantity 
     
     
        being between 0.4 and 0.8 liter. 9. A process for lubricating a surface according to claim 1, the apparent porosity of the layer of particles .[.before the dropping.]. being between about 90% and 98% .[.and 
     
     
        preferably between 95% and 98%.].. 10. A process for lubricating a surface according to claim 1, the porous layer of particles being formed by aggregates of spherules having a diameter of between 5 and 50 nanometers and macrostructures having filaments whose length is between 0.5 and 5 .[.m.]. .Iadd.μm .Iaddend.and whose diameter is between 0.1 and 0.5 .[.m.]. .Iadd.μm.Iaddend.. .Iadd.11. A method of lubricating a surface of an object, in which there is periodically deposited on said surface a layer of lubricant containing carbonaceous particles produced from a gaseous hydrocarbon, comprising the steps of injecting said hydrocarbon for a given period of time through a flame of a temperature higher than 2000° K. produced by combustion of a mixture of hydrocarbon and oxygen, said flame having an oxygen factor greater than 1 and said injected hydrocarbon comprising at least 15% of a constituent of which the ratio of the number of carbon atoms to the number of hydrogen atoms (C/H) is greater than 0.75; and controlling the rate of injection of the hydrocarbon through the flame and the temperature of said flame to obtain a porous layer of carbonaceous particles..Iaddend. .Iadd.12. A method of lubricating a surface according to claim 11, wherein the temperature of said flame is higher than 2500° K..Iaddend. .Iadd.13. A method of lubricating a surface according to claim 11 wherein the oxygen factor of said flame is between 1.1 and 1.4..Iaddend. .Iadd.14. A method of lubricating a surface according to claim 11 wherein the ratio C/H is at least equal to 1..Iaddend. .Iadd.15. A method of lubricating a surface according to claim 11 wherein the hydrocarbon injected through the flame is selected from the group consisting of acetylene, propyne, benzene, acetylene-ethylene mixtures, mixtures made up from propyne-propadiene-propylene and other C 3  and C 4  hydrocarbons..Iaddend. .Iadd.16. A method of lubricating a surface according to claim 11 wherein the hydrocarbon injected through the flame is an acetylene-ethylene mixture at a ratio of approximately 20% by volume of acetylene and 80% by volume of ethylene, and wherein the temperature of the flame is higher than 2,200° K..Iaddend. .Iadd.17. A method of lubricating a surface according to claim 11 wherein successive quantities of hydrocarbon are injected through the flame, each said quantity being between 0.4 and 0.8 litre..Iaddend. .Iadd.18. A method of lubricating a surface according to claim 11 wherein the apparent porosity of the layer of carbonaceous particles deposited on said surface is between 
     
     
        approximately 90% and 98%..Iaddend. .Iadd.19.  A method of lubricating a surface according to claim 11 wherein the porous layer of carbonaceous particles is formed by aggregations of spherules of a diameter between 5 and 50 nanometers and macrostructures having filaments of a length between 0.5 and 5 μm and a diameter between 0.1 and 0.5 μm..Iaddend. .Iadd.20. A method of lubricating a surface according to claim 11 wherein the hydrocarbon is injected at a rate on the order of 170 m/s to 240 m/s..Iaddend. .Iadd.21. A method of lubricating a surface according to claim 11 wherein said surface is a mold for the production of a glass object..Iaddend. .Iadd.22. A method of lubricating a surface according to claim 11 wherein said surface is the surface of a conveyor belt..Iaddend. .Iadd.23. A method of lubricating a surface according to claim 22, wherein the step of injecting comprises injecting said hydrocarbon through a plurality of flames..Iaddend. .Iadd.24. A method according to claim 23 wherein the flames form a curtain, are evenly distributed and are directed perpendicularly to said conveyor belt..Iaddend.