Chlorine alloying element

Further studies include the application of Ru, Rh, Pt, and Ir as second metallic alloying elements (65, 91-93, 96-99). The Pd4 Ir )Pi9 amorphous alloy is the best composition, which has higher catalytic activity for chlorine evolution and lower activity for oxygen evolution than the commonly used Ru02/Ti (Table I). The catalytic activity of Pd-Ir-P can be further improved by adding a small amount of a third metal sometimes together with titanium (Ti and Rh or Ti and Ru) (Table I) (92, 96). 

Ruthenium is a hard, white metal. It does not tarnish at room temperature and is not attacked by acids, not even aqua regia. If potassium chlorate is added, however, the reaction is explosive. Ruthenium is used as an alloying element for platinum and palladium, making these metals harder by soluhon hardening. Such alloys have a high resistance to wear and are used in the manufacture of tips for fountain-pen nibs. A content of 0.1% Ru in titanium improves the corrosion resistance of this metal. Stable anodes for chlorine production are made of titanium, coated with ruthenium. A new technique for improved storage capacity on hard disks uses ruthenium. 

Ruthenium is used as an alloying element for platinum and palladium, making these metals harder by solution hardening. A content of 0.1% Ru in titanium improves the corrosion resistance of this metal. Stable anodes for chlorine production are made of titanium, coated with ruthenium. 

In special cases where the surface hardness must be increased or chemical corrosion resistance is necessary (e.g. plasma etching with chlorine), anodized aluminum surfaces can be useful. Alloying elements, impurities, and heat treatment can influence the nature and quality of the anodized coating - typically, the more pure the aluminum alloy, the better the anodized layer. To build up a thick anodized layer on aluminum, it is necessary for the electrolyte to continuously corrode the oxide, producing a porous oxide layer. ASTM Specification B-580-73 designates seven thicknesses (up to 50 microns) for anodization. 

As a rule, however, the chlorides are the most convenient salts for electrolysis. From the known fact that the melting-point of a compound is lowered by the presence of an impurity, it is often found advantageous to electrolyse a mixture of chlorides rather than a pure chloride in this case one of the elements is liberated in preference to the other. As the anode has to withstand the action of chlorine, it is always made of carbon, which does not unite with chlorine directly the kathode may be of iron, a metal which has no tendency to form alloys with those which are prepared in this way, at least at the temperatures required. The kathode may be the iron pot in which the chloride is kept fused. 

Elemental chlorine is obtained by the electrolysis of molten NaCl (Downs cell). Elemental fluorine is obtained by the electrolysis of KHE2 in a cell made of Monel metal (a stainless steel alloy). Both of these processes are dangerous. Why ... 

Chlorine, sulfur and zinc are potentially harmful chemical elements. Paints and crayons used to mark susceptible alloys must contain low quantities (measured in parts per million, or ppm) of the harmful chemical elements. Less than 100 ppm is allowable. Even if approved marking materials are used, they should be removed from areas that are to be welded, brazed or soldered. An approved solvent such as a non-chlorinat-ed type should be used to remove marking materials. The same principles apply when adhesive-backed tapes are used to fix items to stainless and nickel alloy products (e.g., for radiography). All traces of adhesive must be removed from the surface with an approved solvent. There are no restrictions on using fiber tip markers because they do not leave solid residue. Solvent removal is not required with fiber tip markers. 

X-Ray and SEM measurements indicate that during anodic polarization there is a preferential, fast dissolution of the palladium-rich phases from the crystalline alloys whereas the surfaces of the amorphous alloys remain unchanged (65). Detailed XPS studies revealed that the amorphous alloys are passivated by the formation of a thick, passive film on the alloy surface (65, 96). This film is enriched in the ions of the second metallic element (65, 96, 98, 99), and the activities of the alloys increase almost linearly with the concentrations of the platinum group cations in this surface layer (95), suggesting that these ions are the active sites in chlorine evolution. The fact that the surface film is formed in the gas evolution... 

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