Development of wear-resistant coatings for automotive parts after processing in SHS conditions

Methods of obtaining chromium-coated coatings are considered and technology for the formation of boron, silicon and titanium protected layers on steels under conditions of self-propagating high-temperature synthesis is presented. Using the methods of mathematical modeling, when obtaining wear-resistant coatings on machine parts in conditions of self-propagating high-temperature synthesis, optimal compositions of SHS mixtures have been developed. When tested in sliding friction conditions, the best abrasion resistance, among the coatings under consideration, are chromoaluminium-coated coatings. Their wear resistance is 4.8-5 times higher than in uncoated samples, chromoaluminosilicated and chromoalumotated in 2.1-3.5. The gas-transport method of coating with the help of SHS makes it possible to obtain steel 50 and U8A with increased physical and mechanical properties, without requiring high energy costs and time

Дослідження властивостей ресурсозберігаючої хромвмісної брикетованої легуючої добавки із рудної сировини

It was determined that the original oxide chromium-containing ore raw material is represented by granules of rounded shape the size of 250–600 µm. Along with Cr and Fe, it revealed Mg, Al, Si, Ca, and Ti. They probably were included in the composition of oxide ore impurities and can exert an indirect influence on the reducing processes. Phase composition of the briquetted raw material after the carbon thermal treatment consisted mainly of Cr2O3 and metal Cr with the presence of carbides Cr7C3 and Cr2C3. Diffraction maxima of metal Fe and its compounds had no explicit manifestation, indicating the presence of Fe as substitution atoms in the chromium-containing phases and compounds. The structure is heterogeneous.The content of residual oxygen confirms the presence, along with metal Cr, under-reduced oxide or oxy-carbide compounds. The residual oxygen could also be contained in the composition of oxide related ore impurities. This is confirmed by detection of the specified elements in the examined areas in the images of the microstructure. Excessive carbon content ensures the post-reduction of residual oxide component in a liquid metal in the process of alloying and enables protection against secondary oxidation of chromiumИсследованы фазовый состав, микроструктура хромсодержащего оксидного рудного сырья и соответствующих продуктов углеродотермического восстановления. Опытно-промышленным путем получен ресурсосберегающий хромсодержащий брикетированный легирующий материал с качественно новыми свойствами. Выявлена неоднородная оксикарбидная структура с избыточным содержанием углерода, что обеспечивает довосстановление остаточной оксидной составляющей при легировании и защиту от вторичного окисления хромаДосліджено фазовий склад, мікроструктуру хромвмісної оксидної рудної сировини і відповідних продуктів вуглецевотермічного відновлення. Дослідно-промисловим шляхом отримано ресурсозберігаючий хромвмісний брикетований легуючий матеріал з якісно новими властивостями. Виявлено неоднорідну оксикарбідну структуру з надлишковим вмістом вуглецю, що забезпечує довідновлення залишкової оксидної складової при легуванні та захист від вторинного окислення хром

Study Into Properties of the Resource­saving Chromium­containing Briquetted Alloying Additive From Ore Raw Materials

It was determined that the original oxide chromium-containing ore raw material is represented by granules of rounded shape the size of 250–600 µm. Along with Cr and Fe, it revealed Mg, Al, Si, Ca, and Ti. They probably were included in the composition of oxide ore impurities and can exert an indirect influence on the reducing processes. Phase composition of the briquetted raw material after the carbon thermal treatment consisted mainly of Cr2O3 and metal Cr with the presence of carbides Cr7C3 and Cr2C3. Diffraction maxima of metal Fe and its compounds had no explicit manifestation, indicating the presence of Fe as substitution atoms in the chromium-containing phases and compounds. The structure is heterogeneous.The content of residual oxygen confirms the presence, along with metal Cr, under-reduced oxide or oxy-carbide compounds. The residual oxygen could also be contained in the composition of oxide related ore impurities. This is confirmed by detection of the specified elements in the examined areas in the images of the microstructure. Excessive carbon content ensures the post-reduction of residual oxide component in a liquid metal in the process of alloying and enables protection against secondary oxidation of chromiu