Process of Strengthening Titanium
Aluminum Carbide
The common problems that arise
during processing of these ternary carbides are inadequate densification and
presence of impurities. To improve the density and purity of the max phases,
now a day’s many methods have come which incorporate the use of external
pressure during sintering of the powder particles.
There are various process that are commonly employed for ceramic production. Few of them are mentioned below:
Hot Pressing Method - Powder is placed in a graphite die inside a vacuum chamber, and simultaneously uniaxial pressure, and high temperature either by direct heating or induction heating, are used to compact and sinter the powder at once
Advantages of hot pressing method:
High sintering density, high bonding strength, compaction and
sintering steps are combined, production rate less than 15 minutes, low
pressure (around 20-30Mpa)
Limitations of hot pressing method:
High temperatures (around 14000C) are involved,
expensive, uneven heating that can result in development of thermal stresses
Spark Plasma Sintering - This is a modification of hot pressing (HP) process in that pulsed DC electric field is used to heat the powder particles rather than direct heating or induction heating in the hot pressing process.
The advantages of SPS process:
Fast sintering, uniform sintering, low grain growth, compaction
and sintering stages are combined, Better purification, low pressure
Limitations of SPS process:
Only simple symmetrical shapes can be prepared, Expensive.
There various techniques that are used to strengthen the tertiary carbide ceramic, couple of them are mentioned below
Multiphase strengthening
Along with the efforts to synthesize these carbides, many researchers have attempted to reinforce these compounds with other ceramic materials to improve its high temperature mechanical properties have been reported. Among reinforcing ceramic materials, Aluminum Oxide has been chosen frequently to enhance the properties due to the high hardness, modulus and excellent chemical stability of Aluminum Oxide.
Solid solution strengthening
Solid solution is another method to strengthen carbides by substituting Titanium with Vanadium to form their relative compounds [Meng, F.L., Y.C. Zhou, and J.Y. Wang, Strengthening of Ti2AlC by substituting Ti with V. Scripta Materialia, 2005. 53(12): p. 1369-1372.]. The properties are improved by strengthening the chemical bonds and electronic structure using the above mentioned elements. Solid solution is one of the effective methods to adjust the bonds and structure.
Hydraulic pilot valve
The objective of this project is to develop a small micro solenoid pilot valve of a 1 inch in length and 1/4 inch is diameter that would have be 3 Way and 2-position valve to prevent contamination and leak. There were 5 design that broached into suffice the criterion.
FEM was sued for the evaluation of the critical region that may yield on application of 5 kpsi. The image below gives one the regions that is a high stress region, but are still under the yield stress.
