You need to read books from 1900. They talk about tool steel, valve steel, type metal, and so on. This terminology pre-dates standardization. Some of the names have stuck and become standard, music wire, spring wire, but most have become general terms and not specific alloy descriptions.
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Still trying to help you stop corrosion.
formerly Trent Tube, now Plymouth Tube
eblessman@plymouth.com
or edstainless@earthlink.net
Thanks Nick and Ed. But the "valve metal" I'm talking about is the substrate of an anode, as described below...
These anodes are often referred to as composite anodes. Physically, this term refers to a ductile, corrosion resistant base metal covered with the highly conductive stable film described above. The base metal, titanium, provides the required toughness for the system. The titanium substrate is classified as a "valve metal" or film forming metal. Such metals in their natural state are protected by thin, self-healing, tightly adherent oxide films which are acid resistant and resist the passage of current in the anodic direction. Thus, if an attempt is made to operate a valve metal as an anode, it is necessary to raise the potential of the valve metal surface to a high value in order to pass significant current through the anode.
Modified oxygen reduced valve metal oxides - Patent 6639787Pressed material such as anodes are described and formed from oxygen reduced oxide powders using additives, such as binders and/or lubricants.
Of absolutely no help to you: Valve metal in my industry refers to CDA #844 brass, a highly leaded Cu/Zn alloy, has good casting (low porosity) and machinability characteristics.
I would agree with sreid, that in your case the derivation probably comes from the old (British?) term for electronic vacuum tubes.
The Valve in your statement is the characteristic of these anode material to reform the surface oxide. These materials must be combined with other materials to create a situation where you will get a current and the tend to be self regulating with respect to dissolution rate and current. They require a certain voltage to 'turn the valve on'.
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Still trying to help you stop corrosion.
formerly Trent Tube, now Plymouth Tube
eblessman@plymouth.com
or edstainless@earthlink.net
