- Joined
- Apr 12, 2021
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- 3
A little further explanation of the oxidation aspects of the metal matrix as it relates to sharpening and keeping an edge. Think of the edge as being tiny grains of ceramic projecting from and set in metal matrix. As both Titanium or aluminum have strong affinities to oxygen, in water or in air, they will oxidize. This layer of oxidation is what gives them their corrosion resistance. It is actually very much like an anodizing process... and the grains of matrix have formed microscopic attachments of oxide products... these oxides are what give the material, in general, its corrosion resistance, and form rapidly and are insulators that prevent galvanic corrosion. These look under a electron microscope like a coating of pine cones more or less evenly covering the surface but as with pine cones over a surface there are paths to the actual metal surface, or gaps in the oxide layer on the smallest scale. So molecules of oxygen can reach the surface of the metal matrix between the pine cones like growths of corrosion, but there is not enough room to form another pine cone like structure, as theses have a range of sizes possible. So in these gaps of the oxide layer poultice (pronounced Pot-ice) corrosion happens causing a hydroxide to clog the surface gaps between the little pine cone like corrosive products, when aluminum is anodized it is dipped in boiling water as a last step to pre-seal the little roughnesses in the oxide layer caused by the spread out but tightly spaced oxide pine cones. This prevents further corrosion. Reactivity is related to atomic electric charge on the atoms, in pure water, hydrogen is neutral with 0.0 electron volts and in the negative charge, anodic or less noble direction tin is the is only slightly more neutral with -0.136 electron volts... while iron is -0.4 electron volts, aluminum is -0.1663 electron volts, and the worse are magnesium -2.363 and sodium at -2.714. Silver is actual in the other direction or cathodic more noble direction having +0.799 electron volts. Aluminum is one of the most reactive metals with oxygen and without this would quickly disappear as corrosion... corrode away... in fact it is far worse than bare mild steel, only slightly above magnesium the most reactive, but the oxide layer is very tightly attached, once it forms, and provides great insulation to the potential difference that drives galvanic corrosion. Titanium is is -1.628 electron volts in the anodic or less noble direction but its oxide film is hugely strongly attached, even more than aluminum. These potentials are in water but in various acids and bases you may see electron potentials very high -100.0 electron volts but if the oxide layer exists it insulted them both from attack or basically forming a barrier.
So what all that means is the size of the particles of the materials is very critical to sharpness. If the materials are too large of grains the spaces separating the ceramic can fill up with corrosion products, and wearing away the matrix has to be controlled carefully in the honing or sharpening process, by the type and size of the material abrading the matrix, here titanium away. Shaping the edge to form the best structural and sharpness it does not matter much what is used if it can grossly wear the material, but surface finish produced and the size of the lapping grains of abrasive to expose the matrix must be right for the matter or you may be going backwards. Using diamond paste lapping compound is bad as it would be too aggressive and remove the ceramic particles with the matrix... using the water stones recommended is based on getting the right wearing away of the metal matrix from the ceramic... to leave the ceramic grains imbedded in the matrix and firmly attached while wearing away the titanium matrix between them... so follow directions and recommendations closely... don't second guess. As to reshaping the edge the Japanese understand that far better than you will too.
The doing...
Remember these are engineered materials... so the processes of making, maintaining, and use are engineered in and variance will result in poor results. And, no Japanese stone maker worth his salt would sell a decent stone to someone not knowing how to sharpen. Further, as engineered materials these knife materials are designed for the use intended... which is not as shavers of forearms... they have razors for that... and sharpness is relative to the use intended.
So what all that means is the size of the particles of the materials is very critical to sharpness. If the materials are too large of grains the spaces separating the ceramic can fill up with corrosion products, and wearing away the matrix has to be controlled carefully in the honing or sharpening process, by the type and size of the material abrading the matrix, here titanium away. Shaping the edge to form the best structural and sharpness it does not matter much what is used if it can grossly wear the material, but surface finish produced and the size of the lapping grains of abrasive to expose the matrix must be right for the matter or you may be going backwards. Using diamond paste lapping compound is bad as it would be too aggressive and remove the ceramic particles with the matrix... using the water stones recommended is based on getting the right wearing away of the metal matrix from the ceramic... to leave the ceramic grains imbedded in the matrix and firmly attached while wearing away the titanium matrix between them... so follow directions and recommendations closely... don't second guess. As to reshaping the edge the Japanese understand that far better than you will too.
The doing...
Remember these are engineered materials... so the processes of making, maintaining, and use are engineered in and variance will result in poor results. And, no Japanese stone maker worth his salt would sell a decent stone to someone not knowing how to sharpen. Further, as engineered materials these knife materials are designed for the use intended... which is not as shavers of forearms... they have razors for that... and sharpness is relative to the use intended.
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