Research of surface wettability of plating on the ceramic shell
The wettability of coating surface has important significance in the spreading situation of piece of sticky piece, and the welding state of Au-Sn solder. Wettability of solids is expressed with wetting contact angle. In this paper, by studying the wetting angles of the water droplets on the surface of the different ceramic shell, assess the wettability on the surface of the ceramic shell, and the ways to improve the wettability is proposed through experiments. The results of the experiment show that the presence of organic matter reduces the wettability of the coating surface, so the wetting angles of the coating surface are large in the analysis process. After the plasma cleaning, organics were washed subsequently, and the wettability of the surface coating increased, so the wetting angles are decreased.
The wetting behaviour of several organic liquids in water on coal surfaces
Abstract Several organic liquids were used to probe the surface chemical characteristics of five coal types ranging in rank from brown to low-volatile bituminous in the presence of water. The liquids were hexane, cyclohexane, diiodomethane, toluene, o-xylene, chloroform, dichloromethane, oleic acid, chloroform and hexan-1-ol. The advancing and receding contact angles formed at the coal-water-liquid junction were measured and it was found that a critical interfacial tension existed, below which the organic liquid wetting properties were equivalent. Above the critical interfacial tension, the wettability of the coal by the organic liquid increased as the polarity of the liquid increased, giving a measure of the efficiency with which the water wetting film could be expelled from the coal surface. At a fixed interfacial tension, the advancing and receding contact angles decreased as the rank of the coal increased.
The crystal structure of stilpnomelane. Part II. The full cell
Summary The structural formula of stilpnomelane averaged from 37 representative literature analyses and based on the determined structure is (Ca,Na,K)4(Ti0·1Al2·3Fe35·5Mn0·8Mg9·3)[Si63Al9](O,OH)216·nH2O. Ferrostilpnomelanes have up to 12 R 3+ cations in the octahedral sheet, ferristilpnomelanes commonly have between 24 and 30 R 3+ cations, rarely up to 37. The two groups can be distinguished by accurate X-ray powder diffraction, ferrostilpnomelanes having d 001 less and a greater than have ferristilpnomelanes. The unit cell is triclinic, a = b∼21·8 Å, γ = 120°, d 001∼12·2 Å, P . Hexagonal groups or ‘islands’ of 24 silicon-oxygen tetrahedra co-ordinate to the octahedral sheet, the centres of the ‘islands’ are displaced by 5a/12, 8b/12 on either side of the octahedral sheet as a result of warping of this sheet to permit articulation with the smaller tetrahedral sheet. The 24-tetrahedra ‘islands’ are linked laterally by 6-member rings of inverted tetrahedra, which in turn link at their apices to like rings connecting the next sheet of ‘islands’. Thus a single tetrahedral layer is 4 tetrahedra thick and has symmetry 6/m. The 6-member rings of tetrahedra act as hinges permitting up to 0·5 Å extension or contraction of the tetrahedral sheet to accommodate variations in the octahedral sheet dimensions with varying R 2+/R 3+ ratio.