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

Hydraulic jack, explain the operation manual of a hydraulic jack

explain the operation manual of a hydraulic jack

Disc clutch friction warpage-clutch jerking, Disc clutch friction warpage: ...

Disc clutch friction warpage: Place the disc clutch friction on the surface plate and check for warpage.

Determine the loss of information during exchange in iges, Determine the Lo...

Determine the Loss of Information During Exchange in IGES Loss of Information During Exchange : Information would inevitably be lost when information is passed between two CAD

Objectives of motorcycle servicing , Objectives After studyingmotercyc...

Objectives After studyingmotercycle servicing, you should be able to appreciate the importance of regular servicing and maintenance of a motorcycle and also to recommen

Consideration for centrifugal tension, Consideration: 1. From above eq...

Consideration: 1. From above equation, it is clear that centrifugal tension is not dependent of T1 and T2. It depends upon velocity of the belt. For lower belt speed (that is,

What are the advantages of gear drive, In general, gear drive is useful for...

In general, gear drive is useful for power transmission among two shafts, which are near to each other (at most at 1m distance). In addition, it has maximum efficiency whereas tran

Design study, how to produce a design that meets the specification given: B...

how to produce a design that meets the specification given: Beam Dimensions W, H and T, where H=2W and T=W/20 • Bolt Size D1 • Side Plate thickness T2 and width W2 • Cradle Plat

List and explain the five stages of change, List and explain the five stage...

List and explain the five stages of change. What stage are you at in regards to your own exercise program and explain why? (50-100 words) Refer to page 4 of The Essential Guide to

Evaluate the heat input per day, The input-output curve of a 60 MW power st...

The input-output curve of a 60 MW power station is provided by : I = 10 6 [8 + 8L + 0.4L 2 ] Kcl/hour where I is the input in the Kcal/hour and L is the load in MW. (a) Ev

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