Aluminum alloys, properties

Fluorosulfuric acid can be very corrosive. A study of the corrosive properties of fluorosulfuric acid during preparation and use showed carbon steel to be acceptable up to 40°C, stainless steel up to 80°C, and aluminum alloys up to 130°C (52). 

Lead—Calcium-Tin Alloys. Tin additions to lead—calcium and lead—calcium—aluminum alloys enhances the mechanical (8) and electrochemical properties (12). Tin additions reduce the rate of aging compared to lead—calcium binary alloys. The positive grid alloys for maintenance-free lead—calcium batteries contain 0.3—1.2 wt % tin and also aluminum. 

Table 24. Long Transverse Properties of Wrought Aluminum Alloy Products...

Uses. In spite of unique properties, there are few commercial appUcations for monolithic shapes of borides. They are used for resistance-heated boats (with boron nitride), for aluminum evaporation, and for sliding electrical contacts. There are a number of potential uses ia the control and handling of molten metals and slags where corrosion and erosion resistance are important. Titanium diboride and zirconium diboride are potential cathodes for the aluminum Hall cells (see Aluminum and aluminum alloys). Lanthanum hexaboride and cerium hexaboride are particularly useful as cathodes ia electronic devices because of their high thermal emissivities, low work functions, and resistance to poisoning. 

Alpha—beta aluminum alloys respond to heat treatment with a general improvement of mechanical properties. Heat treatment is accompHshed by heating to 815—870°C, quenching in water, and reannealing at 370—535°C, depending on the size and section of the casting. Different combinations of strength, hardness, and ductility can be obtained. Some nickel in aluminum bronze is in soHd solution with the matrix and helps refine the precipitate, and a smaller amount is in the K-intermetaUic compound. 

It should be noted that a number of aluminum alloys are available (see Table 28-16). Many have improved mechanical properties over pure aluminum. The wrought heat-treatable aluminum alloys have tensile strengths of 90 to 228 MPa (13,000 to 33,000 Ibf/in ) as annealed when they are fuUy hardened, strengths can go as high as 572 MPa (83,000 Ibf/in"). However, aluminum alloys usually have lower corrosion resistance than the pure metal. The alclad alloys have been developed to overcome this snortcoming. Alclad consists of an aluminum layer metaUurgicaUy bonded to a core alloy. 

Table 6-3 Composition (wt.%) and properties of aluminum alloys for anodes...

Table 3.30. Typical Properties of Fully Annealed Nonheat-Treatable Aluminum Alloys...

Heat treatment is an integral part of aluminum forming and is practiced at nearly every plant in the category. It is frequently used both in-process and as a final step in forming to give the aluminum alloy the desired mechanical properties. The general types of heat treatment applied are as follows ... 

Relatively little attention has been devoted to the direct electrodeposition of transition metal-aluminum alloys in spite of the fact that isothermal electrodeposition leads to coatings with very uniform composition and structure and that the deposition current gives a direct measure of the deposition rate. Unfortunately, neither aluminum nor its alloys can be electrodeposited from aqueous solutions because hydrogen is evolved before aluminum is plated. Thus, it is necessary to employ nonaqueous solvents (both molecular and ionic) for this purpose. Among the solvents that have been used successfully to electrodeposit aluminum and its transition metal alloys are the chloroaluminate molten salts, which consist of inorganic or organic chloride salts combined with anhydrous aluminum chloride. An introduction to the chemical, electrochemical, and physical properties of the most commonly used chloroaluminate melts is given below. 

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