Material displacements

Scratch Te.st. The scratch microhardness test is a refinement of the Mohs test. The corner of a cubic diamond is drawn across the surface of a metaHographicaHy poHshed sample under a constant load, usuaHy 29.4 N (3 kgf). The width of the resultant Vee groove scratch varies inversely with the hardness of the material displaced where H = scratch hardness number and A = groove width in micrometers. 

Although Vickers and DPH microhardness tests should yield the same numerical results on a given material, such is not always the case. Much of the observed variance may be a function of differences ia the volume of sample material displaced by the macro and micro iadentations. 

Stationaiy. shell or trough. There are a number of different types of mixers in which the container is stationary and material displacement is accomplished by single or multiple rotating inner mixing devices. 

Continuous analysis requires flexible tubes which are not attacked by the materials under examination, and this places certain limitations on the scope of the method. Certain reactive and corrosive materials cannot he satisfactorily pumped, although advances have been made in the development of inert plastics and other synthetic materials. Displacement pumping with the aid of a liquid compatible with sample and reagents provides an alternative, though generally inconvenient, approach. No such limitations arise in discrete analysers because there is no restriction on the choice of materials for sample and reagent containment. 

The secondary variables, such as shear rate, mean residence time, power consumption, throughput rate, etc., are expressed as a function of the primary variables. For example, the shear rate (or material displacement rate) in the screw channel is a function of the primary variables D, N, and H... 

Purification of Platinum Residuum. The procedure was identical to that described above for Wollaston s second process, with all quantities scaled down to an initial weight of 0.77 g residual platinum. There was, however, insufficient material displaced by iron in the final stage to permit its analysis. 

But not all the material displaced by the generation of grooves separates as loose debris only a fraction of the asperity contacts detaches wear particles, so that... 

Characterization of Displaced Protein. With labelled antithrombin III, chromatography of the displaced radioactivity on heparin-Sepharose revealed that the bulk of the displaced radioactive material did not bind to heparin-Sepharose (Table II). With arvinized plasma as the displacing eluent, 65% of the antithrombin III eluted in the void volume, compared with 49% of the control I-antithrombin III (diluted in citrated plasma) that had not previously been used to inactivate thrombin the latter unbound fraction was likely labelled impurities or inhibitor modified by radiolabelling to lose its heparin affinity. With 5% (w/v) albumin used as a displacing eluent, 78% of the I-antithrombin III came out in the void volume. This increase in material that did not bind to heparin after displacement from heparin-PVA was attributed to post-complex antithrombin III, a modification of the original inhibitor resulting from the inactivation of thrombin. Neither thrombin-antithrombin III complex nor free antithrombin III were detected in the 5% (w/v) albumin displaced fractions while there was a barely detectable amount of complex (6%) and free antithrombin III (4%) in the material displaced by arvinized plasma. With the control I-antithrombin III, 25% of the radioactivity was determined to be free antithrombin III and 2% as complex. The remainder (22-27%) was not recovered from the column. 

During stage 1, the pin is extended past the shoulder to a distance that ensures a constant volume exchange between the material displaced by the pin and that accepted beneath the... 

Various geometries may be used to provide model asperity deformations Tabor (12,13) has reviewed these in several definitive papers mainly in the context of metals. Currently we favour the use of cones as they are a relatively simple geometry to fabricate. Figure 1 is a sketch adopted from Archard (14). If we neglect the volume of material displaced out of the plane of the polymer surface,two very simple expressions for the friction, f, and "wear", W, may be obtained (8,9). The "wear" is not the volume removed but the volume displaced the product of the cross section area of the groove. A, and its length Jl, (Figure 1)... 

Polymer-metal friction pairs are also characterized by frictional transfer of material. This implies the material displacement from the polymer part friction surface onto that of the metal counterbody. Macrotransfer is realized either as a fatigue detachment of polymer particles sticking to the counterbody or as galling, i.e. sticking of the viscous-flow fragments from the polymer surface layer, their extension and movement in the friction direction. 

Figure 11 presents typical AFM results for the early stages of hole formation obtained from the thinnest films investigated. Due to the many holes of similar size formed within the small area detected by AFM, these films allowed us to conclude that most holes were formed within a narrow time interval at the very beginning. At such early stages, the material displaced from the dewetted areas was not collected in visible rims around these areas but was distributed evenly within the whole film in between the holes. Thus, imposing mass conservation, the film thickness between the holes had to increase. A comparison between the thicknesses before annealing as measured by ellipsometry and the depth of the holes measured by AFM is shown in Fig. 12. 

---