Papers by Keyword: Blackening

Abstract: In this paper, the high strength room temperature blackening film on steel surface were prepared, the structure and the forming principle of the film were studied. The procedure of the Cu-Se-P system high strength composition blackening was researched, and the factors that affect the wear resistance of the film were analyzed [1]. The experiment shows that the procedure have many virtues, such as short treatment time, high efficiency, low cost, high adhesive strength, perfect wear resistance, which posed a new approach for blackening of machine parts.

Abstract: With antimony trichloride, tartaric acid, sodium molybdate, hydrochloric acid, sodium silicate as the main raw material, a black chemical conversion coating treatment process was developed in the steel surface by the impregnation method at room temperature, and analyzed the films by SEM, XPS, XRD method. The results showed that: the film was a single black mass of antimony-based, and contains a small amount of Al2O3•2SiO2•3H2O crystal composite coating. It showed the crystalline structure in the scanning electron microscope, then preliminary analysis the mechanism on this based.

Abstract: The paper presents some preliminary experimental results dealing with electrochemical synthesis and corrosion behavior of various black layers types onto Al substrates, suitable to be used as selective absorber coatings in the case of thermal energy production from solar energy, involving several different procedures, respectively: (i) electrodeposition of black Ni-Mo alloy after an initial anodizing in nitric acid electrolyte that offers a very good adherence of the further applied coatings; (ii) cathodic deposition of black Mo based layers after an initial double zincating procedure; (iii) black coatings through a.c. electrochemical coloring of aluminum anodic oxides, using AgNO3/H2SO4, NiSO4 based solutions; (iv) black composite polypyrrole films. The obtained black layers are characterized by a good throwing power, homogeneity, smoothness and adherence, as shown by SEM and AFM investigations. Also, they present a good solar absorption and low values of infrared emittance. To evaluate the resistance of black coating layers against corrosion, several accelerated corrosion tests have been performed, respectively: (i) continuous immersion in 0.5M NaCl for 408 hours with intermediary visual examinations and recording of corrosion potential; (ii) potentiodynamic polarization curves in 0.5M NaCl; (iii) impedance spectra in 0.5M NaCl at open circuit potential using a Zahner IM6e potentiostatic equipment. The corrosion performances are discussed taking into account the applied preparation procedures.