Mechano-chemical synthesis of titanium silicide with sodium silicate

The goal of this research work is to build up the technology for producing nanostructured ceramic materials with superior mechanical behavior. This combines two important issues: (a) Mechanical Alloying (MA), a high intensity ball milling process to produce nanophase, and (b) Low-temperature Chemical Consolidation, a method for retaining the fine-scale structure of nanoscale powders in bulk materials by using a chemical binder. This chemical binder transforms into an amorphous interface around the nanocrystalline ceramic particles. Nanostructured materials obtained through this process have superior mechanical properties and better resistance to electrochemical attack than conventional materials with grain size in the range of micrometers.; Titanium silicide (Ti₅Si₃) is the most promising ceramic material at elevated temperatures. This ceramic material, in powder form, of 99.95% purity and of 325 mesh size, mixed with steel grinding balls was subjected to mechanical alloying process. A statistical method called factorial design of experiments was used for conducting the milling experiments. This method was also employed to assess the effect of mechanical alloying variables, namely milling speed, ball to powder ratio and milling time on the crystallite size of the mechanically alloyed titanium silicide powder and the microhardness of the samples consolidated by chemical bonding.; X-ray diffraction (XRD) analysis was used to determine the crystallite size of the milled powder. The milled powder was mixed with a chemical binder called Sodium Silicate (Na₂SiO₃), and then cured and tired at reasonably low temperatures. Microhardness test, bend test and compression test were performed on the consolidated samples to determine the mechanical properties of the samples. The results obtained with sodium silicate binder were compared with another chemical binder called AllylHydriodPolyCarboSilane.; The optimum combination of the milling parameters and the proportion of the chemical binder giving a result of fine crystallite size in mechanically alloyed powder and good microhardness in the compact was established. To ensure the preservation of the fine-scale structure, the crystallite size of the consolidated samples was measured using XRD analysis.