Soft material

Bates F S and Fredrickson G FI 1999 Block copolymers—designer soft materials Phys. Today 52 32- 8... 

Ensure that all the individual components in the assembly are adequately supported when in position the friction between contiguous ground-glass surfaces does not provide adequate support. Therefore always use clamps, the claws of which are lined with rubber or other soft material. When assembling apparatus, allow some play in the clamps until the individual parts are in position, and then secure the position of the assembly by gently increasing the pressure of the clamps. 

CO—C H,—CO—0—CHj—CHOH—CHj—OOC—CgH,—CO— These are comparatively soft materials and they are soluble in a number of organic solvents. Under more drastic conditions (200-220°) and with a larger proportion of phthahc anhydride, the secondary alcohol groups are esterified and the simple chains become cross-hnked three dimensional molecules of much higher molecular weight are formed ... 

In the Rockwed test a spheroconical diamond (Brale) indenter or a hardened steel bad is used with various load ranges to achieve a series of scales identified by a suffix letter (Table 3). The suffix letter defines both load and indenter. The most popular scales used are "C" for hard materials and "B" for soft materials. A Rockwed hardness number is meaningless without the letter suffix, eg, HRC 54 or HRB 95. 

Various other soft materials without the layer—lattice stmcture are used as soHd lubricants (58), eg, basic white lead or lead carbonate [598-63-0] used in thread compounds, lime [1305-78-8] as a carrier in wire drawing, talc [14807-96-6] and bentonite [1302-78-9] as fillers for grease for cable pulling, and zinc oxide [1314-13-2] in high load capacity greases. Graphite fluoride is effective as a thin-film lubricant up to 400°C and is especially useful with a suitable binder such as polyimide varnish (59). Boric acid has been shown to have promise as a self-replenishing soHd composite (60). 

The component materials comply with apphcable ASTM specifications, but alter manufacture the outer component may increase in hardness beyond specification limits, and special care is required during the tube-rolling operation. When the harder material is on the outside, precautions must be exercised to expand the tube properly. When the inner material is considerably softer, rolling may not be practical unless ferrules of the soft material are used. 

Soft Materials (1) Talc, dried filter-press cakes, soapstone, waxes, aggregated salt ciystals (2) gypsum, rock salt, ciystahine salts in gener, soft coal (3) calcite, marble, soft limestone, barites, chalk, brimstone. 

Performance The dry pan is usebil for crushing medium-hard and soft materials such as clays, shales, cinders, and soft minerals such as barites. Materials fed should normally be 7.5 cm (3 in) or smaller, and a produc t able to pass No. 4 to No. 16 sieves can be dehvered, depending on the hardness of the material. 

Affected metal is converted to a very soft material that can be dislodged with a sharp metal probe or cut with a knife. Graphitically corroded metal frequently has an oily, shppery feel, especially after surface deposits are scraped away. Because of its graphite content, chunks of corroded metal can be used as writing implements in the absence of a pencil (Fig. 17.4). Graphitically corroded metal will produce a dull thud rather than a metallic sound when struck with a hammer. 

Flinn et al. [30] describes an experimental impact technique in which <100)-oriented LiF single crystals ( 8 ppm Mg) are loaded in a controlled manner and the multiplication of screw dislocations is measured. The peak shear stress in this relatively soft material is 0.01 GPa. For shear impulses exceeding approximately 40 dyne s/cm, dislocation multiplication is adequately described by the multiple-cross-glide mechanism [(7.24)] with m = l/bL = (2-4) X 10 m, in reasonable agreement with quasi-static measurement [2]. 

STM and SFM are free from many of the artifacts that afflict other kinds of profilometers. Optical profilometers can experience complicated phase shifts when materials with different optical properties are encountered. The SFM is sensitive to topography oidy, independent of the optical properties of the surface. (STM may be sensitive to the optical properties of the material inasmuch as optical properties are related to electronic structure.) The tips of traditional stylus profilometers exert forces that can damage the surfaces of soft materials, whereas the force on SFM tips is many orders of magnitude lower. SFM can image even the tracks left by other stylus profilometers. 

JKR-type mea.surements on soft elastomers. In their original paper, Johnson and coworkers [6] reported on adhesion measurements between soft materials. 

To reduce friction and improve compression efficiency, the piston will be provided with segmented compression rings as shown in Figure 11-11. To prevent piston-to-bore contact, the piston may also be provided with removable wear bands that are in continuous contact with the cylinder wall. The compression rings and wear bands are replaced at regular intervals and typically made from soft materials such as brass, Micarta, Teflon, and the newer thermoplastics. 

Figure 12-52A, B, C. A) Straight-pass labyrinth seal B) staggered labyrinth seal C) stepped labyrinth seal. Note Materials usually are aluminum, bronze, babbit, other soft material, or steel. (Used by permission Cooper-Cameron Corporation.)...

To combat this problem, soft materials such as Babbitt are used when it is known that a bearing will be exposed to abrasive materials. Babbitt metal embeds hard particles, which protects the shaft against abrasion. When harder materials are used in the presence of abrasives, scoring and galling occurs as a result of abrasives caught between the journal and bearing. 

Petroklastit or Haloklastit. Ger expl designed for blasting soft materials such as rock salt, etc. 

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