| 摘要 |
<p>1355231 Measuring surface properties of metals and metalloids M ENSANIAN 22 Sept 1971 [8 Oct 1970] 44257/71 Chemical and physical irregularities in the surface of a metal or metalloid are detected by measuring the magnitude and polarity of the voltage generated by a cell comprising a test electrode, a self sustaining body of electrolyte and a small area of said surface. The electrolyte may be carried by saturated absorbent discs or gelatine pellets. As shown in Fig. 3, a non- conductive tape 43 carries absorbent discs (45) saturated with electrolyte and is wound on, one disc at a time, from a supply spool 42 to a takeup spool 48. A trigger and ratchet (not shown) or a spring motor (not shown) may be used to advance the tape. In Fig. 14, the electrolyte is held in tyres on wheel electrodes which roll over the surface being tested. The wheels may have radial protrusions Fig. 13, (not shown). Alternatively Fig. 10, (not shown) the electrolyte carrier may be the entire wheel, the electrode serving as the axle. The tyres Fig. 14 or wheels Fig. 10, (not shown) may be made of felt or woven fabric, paper, wood, natural or synthetic sponge, or porous ceramics saturated with electrolyte, or gelatine or other gelling agent (long list given) mixed with electrolyte. Chemical details of electrodes and electrolytes. The test electrode, or a removable working tip, may be made of the same metal or metalloid as the surface under test, or may be made of a chemically resistive metal, e. g. Pt, Au, Pd, Ta, or graphite. The electrolyte is preferably a soluble salt of the metal being tested, e. g. iron sulphate or aluminium sulphate, but may be a soluble salt of another metal higher in the electro-motive series, e.g. Kcl may be used with Fe or Al electrodes to test iron or aluminium surfaces respectively. Also Li, Na, Ca salts may be used. The concentration of the electrolyte is not critical and may be in the range from 0À000M to 1M. When testing alloy surfaces, e. g. copper-tin (bronze), readings may be taken using a Cu electrode and a Cu salt electrolyte and Sn electrode and Sn salt electrolyte and compared. Both readings may be taken simultaneously, using the apparatus of Fig. 14, alternate wheels being characterized by different metals. Applications. Impurities and corrosion may be detected. Heat treatments or welds may be evaluated. The test surface may be hot, cold, polished or unpolished, and may be that of a casting or a wire or may be a vacuum deposited or plated coating. Sheets and springs may be tested before, during and after bending and tensioning respectively.</p> |
