Carbides, Mechanical Engineering

Assignment Help:

Carbides

Carbides of titanium, zirconium, boron and silicon are significant refractory materials. Though, the carbides have extremely high melting points so they lack oxidation resistance.

Carborundum, a well identified abrasive material is silicon carbide or SiC. Such material has extremely high hardness, high thermal conductivity, extremely high refractoriness, and has semi-conducting nature. Silicon Carbide's electrical conductivity is low at low temperature but raises by order of magnitude at high temperatures. When 60 percent sand and 40 percent coke along with some saw salt and dust and heated in an electric arc furnace at a temperature of about 1425oC, the resulting product is Silicon Carbide. The SiC removed from the furnace is a mass of interlocking crystals. Several shapes may be acquired when SiC is ground, mixed along with binding agent, fixed and shaped. The most widely and oldest utilized is the clay bonded material. Within this material refractory clay is added as the bonding agent. The bond in such combination softens at 1200-1500oC. Silicon and silicon nitride, are other binding materials. Silicon bonded Silicon Carbide also has its employ limited to a temperature below 1500oC due to loss in bond strength. Silicon nitride bonded SiC, though, retains its strength at great higher temperature and shows also much better shock resistance. Though a monoxide, a layer of SiO2 is formed on SiC. Such oxide layer protects SiC from more oxidation. Adding of 0.5 to 1% B throughout sintering helps uniform structure and imparts stability. SiC fibres have been utilized as reinforcement in metal and ceramics. Reaction bonded SiC is made via two distinct processes. In one procedure a compact of SiC, an organic and carbon binder is infiltrated via liquid Si that bonds the particles by formation of additional SiC. The free Si might be leached out along with acid to leave an open porous refractory. Thin walled coating or components of SiC is produced via decomposition of gas mixture containing both Silicon and C on a heated substrate. The fuel elements of high temperature gas cooled elements are produced via this process. Recently slip casting has also been utilized for silicon carbides. It has resulted in products of superior refractoriness, density, abrasion resistance and high strength, and good chemical resistance also. Silicon carbide refractories are characterized via low thermal expansion and high thermal conductivity. They tend to oxidize gradually in air at a temperature range of 900-1300oC.


Related Discussions:- Carbides

Show the types of changes in project, Q. Show the types of Changes in proje...

Q. Show the types of Changes in project? During the development and execution of a project, the following changes can occur:  Scope of work changes  Cost deviation

Theoretical results-conventional priority rules, Theoretical Results I...

Theoretical Results In the particular machine case, several theoretical results are identified or can be derived: (a) If each operation can be scheduled such that everyone

Difficulties with motion sickness, In designing rotating space stations to ...

In designing rotating space stations to give for artificial-gravity environments, one of the constraints that must be considered is motion sickness. Studies have shown that the neg

Stitch welding, Stitch welding Here, a series of overlapping spot welds...

Stitch welding Here, a series of overlapping spot welds are made with the spot welding machine using the conventional electrode tip. Both water tight and gas tight joints can b

Industrial jobs, i wanna know is production job is best or marketing after ...

i wanna know is production job is best or marketing after doing btech

How can you implement permeability test, Q. How can you implement Permeabil...

Q. How can you implement Permeability test  As already defined, permeability of porosity of the moulding sand is the message of its ability to permit air to flow through it.

Determine the water depth - standard step method, Consider a trapezoidal ch...

Consider a trapezoidal channel with a bottom width of 4 m, side slopes of 3:1 (H:V), and a bottom slope of 0.002 that carries 50 cms. The channel has a Manning's roughness of 0.034

Determine the displacement response time, (i) Formulate the equation of mot...

(i) Formulate the equation of motion for the system shown in Figure. List TWO (2) assumptions made in this formulation. (ii) Find the response of this system at t = 3s. The syst

Explain the information phase screw conveyor with auger, Information phase ...

Information phase of screw conveyor with auger: Steps: To secure all and complete information and gather facts and from best sources.Our project is selected based on the cu

Determine the angle of jet, A jet of water moving at 8 m/sec. impinges on a...

A jet of water moving at 8 m/sec. impinges on a concave-shaped vane to deflect the jet through 120 o when stationary. If the vane is moving at 5 m/sec., determine the angle of jet

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd