Technology of Powder Coatings Application by Gas-Flame Spraying Using Oxyhydrogen Flame

In the article the equipment, method and the results of researches of strength of gas-flame coatings cohesion with the base are presented. The dependence of adhesive strength on spraying modes of powder material by oxyhydrogen flame is established and described. Recommendations on choosing the gas-flame spraying modes are developed.

Flame Temperature Distribution and SiO2 Particles Distribution in Oxyhydrogen Flame

In the production process of synthetic silica glass, SiCl4 as precursor is imported in oxyhydrogen flame, SiO2 particles generate and distribute with different states along the flame. The flame temperature and the distance above the burner are important factors to affect the particle diameters and morphologies. The 2D distribution of flame temperature was measured using sodium line-reversal method. The diameters and morphologies of SiO2 particles were analyzed by transmission electron microscopy (TEM) at 50mm, 100mm, 200mm, and 300mm above the burner. The results show that the flame temperature ranges from 2130°C to 2320°C, and the average diameter of SiO2 spherical particles increases from 50nm to 105nm as the distance increasing from 50mm to 200mm. The optimum deposition distance was discussed.

New Universal Quartz Burner for Decomposition of Samples by the Wickbold Combustion Technique in Determination of Arsenic, Antimony, Selenium, Mercury, and Lead

A new universal quartz burner for the Wickbold decomposition method is investigated with respect to its fast and efficient decomposition of solid samples for determining volatile trace elements like arsenic, antimony, selenium, mercury, and lead. Decomposition is based on burning samples in an oxyhydrogen flame. The samples are transported into the flame in gaseous form by pyrolyzing the material in an oven heated to 1100C. During this decomposition step, a nitrogen stream loaded with carbon tetrachloride mobilizes the volatile elements, causing separation from the sample matrix. An effective precombustion in oxygen and a large turbulent flame improve decomposition conditions. Different certified inorganic and organic reference materials are pyrolyzed and combusted, and the combustion products are absorbed in water. Metals found in the absorption solutions are analyzed by flow injection/hydride generation/atomic absorption spectrometry. Data were analyzed by several statistical tests recommended for quality control purposes. The combination of a decomposition and detection method resulted in very low detection limits: 1.4 μg arsenic/kg, 0.8 pig antimony/kg, 1.8 μg mercury/kg, 1.4 μg lead/kg, and 1.6 μg selenium/ g can be detected without an extra enrichment step.