Soft alloys

Type I, soft alloys (20—22-carat golds), are used for inlays of simpler non-stress-bearing types. Type I gold alloys can be burnished, and are not heat-treatable. They are composed essentially of gold—silver—copper with minor modifying additions, eg, zinc. 

A separate study was the improvement of magnetic permeability in soft alloys such as are used in transformers and motors by lining up the orientations of individual crystal grains, also known as a preferred orientation this became an important subspeciality in the design of transformer laminations made of dilute Fe-Si alloys, introduced more than 100 years ago and still widely used. 

Babbit metal. A soft alloy of metals such as tin, silver, arsenic, and cadmium combined with a lead base. It can be cast or used as a coating on steel bearings to form an oil-hke coating that reduces friction. Used to make oil-less bearings. 

Wood alloys (examples 14-18, Table 8). This class includes soft alloys that can absorb a large amount of lithium at relatively low potentials and low voltammetric changes. 

Another tin alloy is Babbitt metal. Babbitt metal is a soft alloy made of any number of metals, including arsenic, cadmium, lead, or tin. 

Babbitt metal. One of a group of soft alloys used widely for bearings. They have good bonding characteristics with the substrate metal, maintain oil films on their surfaces, and are nonseizing and antifriction. Used as cast, machined, or preformed bimetallic bearings in the form of a thin coating on a steel base the main types are lead base, lead-silver base, tin base, cadmium base, and arsenical. The latter contains up to 3% arsenic. 

Typical material that can be spun with a blunt tool will be soft alloys in the annealed condition, such as aluminum, brass, copper, or pewter. This process is generally limited to material less than 0.075 in. thick, but this limit can be increased by using a less blunt tool and a stronger operator. 

Also of interest were such corrosive substances as acids, hydroxides, and ammonium chloride, which on heating turns into ammonia and hydrochloric acid and readily attack metals. Because arsenic sublimes like mercury, forms soft alloys like mercury, and has a sulfide that looks like the sulfide of mercury, alchemists regarded arsenic as a kind of mercury, and much use was made of arsenic s property of coloring metals. Vitriols (copper and iron sulfates) were also of interest to the alchemist, probably because of their colors. Copper sulfate forms beautiful blue crystals and solutions, and iron sulfate is green. We can confidently write about the preceding materials and techniques because of the efforts of a few early alchemical practitioners to preserve their knowledge in writing. Three are considered here pseudo-Democritus, Mary the Jew, and Zosimos. 

Joint area Assembly Surface cleanliness Plastics and soft alloys... 

If one or more of the parts in a bonded assembly is made of a plastics material or soft alloy, then the overall performance will be lower than if the parts had been made of steel. It is important to remember that the shear strength of co-axial joints shown during the displacement of the parts is actually a measure of the bonding and mechanical jamming action of the hardened adhesive. The emphasis on either bonding or jamming depends upon the type of adhesive. 

Stronger grades of adhesive should be used with soft alloy or plastics housings to compensate for reduced jamming action as a result of the increased ductility of the housing (see p.25 Plastics and soft alloys). 

As sleeves are not generally highly loaded in shear they are well suited for retention with anaerobic compositions. Light alloy parts may need the higher-strength grades to compensate for the lower modulus of the metal (see p.25 Plastics and soft alloys). 

Weaker anaerobics should be used with soft alloy nuts and other threaded fasteners to prevent thread stripping during disassembly. Soft alloy and plastics fasteners exhibit a lower removal torque than their steel equivalents, because less hoop stress is generated as the adhesive is crushed during removal. Despite this apparently lower performance (remember removal is only a test method ranking) the parts will still be effectively locked and resistant to vibration. 

A distinction needs to be made here with the observations of Section 2.3.1.3 (p.25), recommending use of the higher-strength anaerobic compositions -preferably those with true adhesive characteristics - to ensure retention of fitted non-threaded parts fabricated from soft alloys and plastics. 

Soft alloy and plastics screws may be locked with anaerobics but the softness of the material will reduce the prevailing torque. If a plastics screw is being placed in a plastics part then a secondary catalyst will be needed in addition to the anaerobic composition. This will normally be an aerosol-based primer or, for large batch quantities, total immersion in the primer may be practicable. 

Solders are typically classified as either soft or hard. Some confusion often results from this convention because some hard solders are really braze materials if the melting temperature criterion is applied. Soft solders typically consist of alloys containing lead and tin, but also often contain indium (In), bismuth (Bi), antimony (Sb), or silver (Ag). In practice, most soft alloys melt at temperatures lower than 450°C, usually between 180°C and 300°C. High-tin solders, typical of lead-free solders, tend to be stiffer, harder, and less ductile compared to high-lead solders. Hard solders often contain metals such as Au, Zn, Al, and Si. 

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