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The debris and the worn surface after dry sliding wear were studied by scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS) and X-ray diffractometry (XRD). A pin-on-disk method, in which the pin was the 15%Al2O3(p)-6061Al composites and the disk was a 52100 steel, was used. The microstructural features for severe wear appeared to be much coarser than those for mild wear. According to the EDS and XRD results, the chemical compositions of the debris for mild wear were different from those for severe wear. The debris for mild wear mainly consisted of ferric oxide (Fe2O3), while the debris for severe wear was composed of Al2O3, Al and α-Fe. Cross-sectional SEM images showed that Al2O3 particles near the composite surface did not suffer obvious deformation. Thus, it seemed to be the Al2O3 particles which make the composite more wear resistant under the mild wear conditions. However, in the severe wear conditions, many Al2O3 particles near the surface were broken off, which prevented them from resisting wear.

Publisher Summary This chapter discusses the manufacturing of polyester fibers. The fiber-forming polyester may be obtained from dicarboxylic acids with diols, hydroxyl acids or lactones. Commercially, aromatic polyester is applied using Ethylene Glycol (EG) and Dimethyl Terephthalate (DMT) or Ethylene Glycol and Terephthalic acid (TPA) to produce Polyethylene Terephthalate (PET). In industrial practice, the polymerization processes of aromatic polyethylene terephthalate are produced via a two-step process. The first step is esterification and preliminary condensation, while the second is polycondensation or melt polymerization. Then, the spinning process of fiber-forming polyester converted to fiber passes into three stages. In the first stage, solid fiber-forming polyester is produced from polymerization, which is called polymer chips. Polyester chips are converted to dope by heat or by dissolving in some solvent. In the second stage, dope fluid is extruded through a spinneret and then converted to viscoelastic filament. The viscoelastic filament is solidified into solid filament fiber, which may be formed by extending the viscoelastic filament. Solidification may be obtained by cooling, by extruding the viscoelastic filament submerged in a coagulation bath for removal of the solvent, or by extrusion into the heating chamber for evaporation of the solvent.

Electrochemical behavior of a YBa2Cu3O7 (YBCO for short) superconductor was studied by potentiodynamic scanning in different aqueous solutions with 0.1 M concentration. The electrochemical stability of the YBC0 compound was found to be superior in sulfurous acid, NaC1, or KC1 solutions. The dissolution potential in the above solutions ranges from 36 – 92 mV, polarization wasn't possible. However, E raised up to 360 – 960 mV in acids corr solutions with oxidizing potential including suluric, phosphoric and nitric acids indicating a passive behavior. Polarization was observed in sulfuric, sulfurous, and phosphoric acids depicting their potential to be used as etching solutions in lithography of this oxide superconductor. Its electrochemical behavior in HC1 solution is peculiar and informative. It shows three transitions in the polarization curve, corresponding to 272, 756, and 1013 mV, respectively. This is probably related to the transition in the valence states of copper ions during dissolution which is suppressed in the oxidizing acids. In comparison with metallic copper, the YBCO is more stable in the above solutions. The Galvanic current decreases at the order of A1 > Cu > Ag, when the YBC0 is coupled with each of them in 1 M phosphoric acid solution.