Fluoroammonium method for processing of cake from leaching of titanium-magnesium production sludge

We present the results of the physical and chemical properties of cake from nitric-acid leaching of titanium production sludge. It was found that all silicon in the cake is in the form of quartz, albite, sillimanite, sodium aluminosilicate. In total, these minerals make up the majority of the cake 60.24%. Titanium is presented in the form of rutile, titanium aluminum oxide, which in total is 35.56%. Iron is part of sillimanite and hematite, the total content of which is about 4.2%. The optimal parameters of fluoroammonium processing of cake were determined: silicon distillation into sublimates at 300°С for 6 hours, sublimation of titanium in the form of titanium tetrafluoride at 800°С for 2 hours. The process of alkaline hydrolysis of sublimates of fluoride compounds and cinder was carried out. Purification of impurities and calcination of hydrated titanium dioxide were carried out. The resulting titanium and silicon dioxide products contain: 96.2% TiO2, 88 % SiО2, respectively; a niobium-containing intermediate product with a content of 11.6 % Nb2O5 was also obtained.

Contact Reactive Brazing of TC4 Alloy to Al7075 Alloy with Deposited Cu Interlayer

The brazing of Titanium alloy to Aluminum alloy is of great significance for lightweight application, but the stable surface oxide film limits it. In our work, the surface oxide film was removed by the ion bombardment, the deposited Cu layer by magnetron sputtering was selected as an interlayer, and then the contact reactive brazing of TC4 alloy to Al7075 alloy was realized. The microstructure and joining properties of TC4/Al7075 joints obtained under different parameters were observed and tested, respectively. The results revealed that the intermetallic compounds in the brazing seam reduced with the increased brazing parameters, while the reaction layer adjacent to TC4 alloy continuously thickened. The shear strength improved first and then decreased with the changing of brazing parameters, and the maximum shear strength of ~201.45 ± 4.40 MPa was obtained at 600 °C for 30 min. The fracture path of TC4/Al7075 joints changed from brittle fracture to transgranular fracture, and the intergranular fracture occurred when the brazing temperature was higher than 600 °C and the holding time exceeded 30 min. Our work provides theoretical and technological analyses for brazing TC4/Al7075 and shows potential applications for large-area brazing of titanium/aluminum.

A Study of the Possibility of Obtaining Deposited Coatings based on Intermetallic Titanium and Aluminum Compounds using the Chemical Vapor Transport Method

Theoretical and experimental investigations of processes of titanium-aluminum coating formation on refractory wire substrates by the Chemical Vapor Transport Reactions (CVT) method were carried out. Modelling of CVT was based on the thermodynamic analysis of an equilibrium iodide system implying the presence of one of titanium aluminides in the condensed phase, titanium and aluminum iodides in the gas phase, as well as atomic and molecular iodine. The fact that the volatility and stability of various metals are strongly interrelated was considered as a working hypothesis, which made it possible to obtain a number of alloys with the simultaneous decomposition of metal iodides constituting an alloy. Experiments on the deposition of titanium-aluminum coatings were conducted in a quasi-closed reactor, which allowed us to obtain deposited coatings on long-length refractory substrates

Failures Related to Hot Forming Processes

The primary purpose of this article is to describe general root causes of failure that are associated with wrought metals and metalworking. This includes a brief review of the discontinuities or imperfections that may be common sources of failure-inducing defects in the bulk working of wrought products. The article addresses the types of flaws or defects that can be introduced during the steel forging process itself, including defects originating in the ingot-casting process. Defects found in nonferrous forgings—titanium, aluminum, and copper and copper alloys—also are covered.

Synthesis of Composite Materials based on TiB2–TiC–Al2O3 and CrB2-Al2O3 in the Combustion Conditions

Borides and carbides attract the attention of developers of heat-resistant and super hard structural materials due to a unique combination of their resistance to high-temperature oxidation, high hardness, wear resistance, electrical and thermal conductivity and etc. The article presents experimental results on obtaining composites based on TiB2-TiC-Al2O3, CrB2-Al2O3 by a method combining self-propagating high-temperature synthesis (SHS) and mechanical activation (MA). The influence of the composition of the initial components, the conditions of SHS and preliminary MA on the formation of the microstructure and phase composition of the SHS-composite based on titanium carbide and titanium, chromium borides has been studied. The SHS products were examined by X-ray diffraction analysis and a scanning electron microscope. High-temperature phases of borides of chromium, titanium, aluminum oxide and their spinel are found in SHS products.