Manufacturing
Ready-to-press and sinterable silicon carbide (RTP SiC) granules
Overview
Ready-to-press silicon carbide (RTP SiC) granules is being produced using spray drying or spray freeze drying technique through an intermediate colloidal processing route. This method is capable of producing different size spherical granules with narrow size distribution and improved flow characteristics. As the granules are produced from uniformly dispersed slurries of SiC powder, hence wide range of additives can be accommodated in the formulation of the RTP granules. This process is beneficial to manufacture the feedstock for producing green SiC compacts with high density, defect free homogenous microstructure. The sintered products thus produced exhibit superior properties than conventionally produced SiC. The technique has been adapted to produce RTP granules comprising water sensitive nitride based composite powders.
Key Features
- Cost effective technique to produce RTP SiC granules.
- Flexibility to incorporate either solid-state or liquid-phase sintering additives in the formulation of RTP granules.
- Control on granule size with narrow distribution
- The process can be adopted for manufacturing various oxide or non-oxide ceramics.
- Up to 97.8 % relative density achieved in the sintered parts.
Potential Applications
- Feedstock for manufacturing of high performance SiC, Si3N4, SiAlON components
Intellectual Property Development Indices (IPDI) 
- RTP granules processed in the laboratory scale
- Scaling up the process is in progress
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Major Patents / Publications
Major Patents
Major Publications
- P. Barick, B. P. Saha, S. V. Joshi and R. Mitra, Spray-freeze-dried nano-crystalline SiC containing granules: processing, compaction behaviour and sintering, J. Euro. Ceram. Soc., 36 (2016), 3863-3877
Dense silicon carbide (SiC) coatings by chemical vapour deposition (CVD) technique
Overview
Theoretically dense SiC coating processed by chemical vapour deposition (CVD) exhibits superior physical, mechanical, thermal and optical properties with excellent wear, abrasion and chemical corrosion resistance. The properties of CVD SiC coating can be tailored by control of various parameters including reactor design, process temperature, pressure, reactants composition and flow geometry. ARCI has established a CVD system for coating of large size components (up to 1.0 m meter) by thermal deposition of methyl-trichlorosilane (MTS) in excess of hydrogen. High density CVD SiC coating on various substrates with different geometries have been produced. It has been demonstrated that the CVD SiC coating can be polished up to the RMS surface roughness < 1 nm. ARCI also has the capability to produce self-standing CVD SiC parts.
Key Features
- State-of-the art CVD SiC coating facility.
- The processes technology has been established
- SiC coating on different size and shapes can be produced.
- CVD SiC coating can be polished to very high surface finish(<1 nm).
Potential Applications
- Reflectors for high energy laser and synchrotron radiation.
- Wear and corrosion resistant coatings
- Reflectors for concentrated solar power (CSP) applications
- Solar collectors and concentrators for astronomical telescopes.
Intellectual Property Development Indices (IPDI)
- The process technology and repeatability have been established.
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Major Patents / Publications
Major Patents
Major Publications
Exfoliated graphite and its value-added products
Overview
The stacked parallel layers in natural graphite flakes (NGF) are separated by 0.34 nm and the layers in a stack are attached or bonded with a weak Van der waal forces. For successful exfoliation, overcoming the van der Waal attraction between the adjacent layers is crucial. The best feasible method is to decrease the attractions by increasing the distance between the adjacent layers via oxidation and chemical intercalating reactions. During oxidation of graphite, the functional groups like hydroxyl, epoxide and hydroxide etc are inserted between the layers leads to increase in d-spacing from 0.34 to 0.70 nm. Due to thermal shock, the functional moieties try to escape and create porous structure is termed as exfoliated graphite (EG). EG can be moulded into various desired shapes (sheets, tapes, seals, and boards) by mechanical compaction without adding any sort of binders. Self-binding capability of the porous-structured material is a unique characteristic of this technology. Our technology demonstrates the production of EG in bulk quantity by chemical intercalation and thermal exfoliation of NGF. It is a cost-effective and continuous process for bulk production.
Key Features
- Binder-free compaction of material
- Shape-tailored material
- Very light weight
- Density-controlled compaction
- Sandwich or reinforced material with better mechanical properties
- Efficient and cost-effective
Potential Applications
- Flexible sheets
- Flexible tapes
- Bipolar plates
- Seals
- Reinforced seals, sheets and tapes etc
- Ultra light weight boards
Intellectual Property Development Indices (IPDI)
- Scale-up and pilot plant is established
- Demonstration of bulk quantity through thermal reactor is done
- Various types of prototype module has been established
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Major Patents / Publications
Major Patents
Major Publications
Refurbishment of Cast Iron Components using Laser Cladding
Overview
Grey cast iron finds extensive applications in the Glass mould industries and automotive industries for making of components like dies, gears, links, cylinder block, cylinder head, clutch plate etc. Many times, the size of the cast component is large and a small localize wear can lead to scrapping the entire component. Repair of cast iron has been very challenging due to presence of free carbon in the form of graphite flakes which forms COx gases during deposition and these gases get entrapped during the deposition process resulting in porosity. Transverse cracking is another deterrent in repair which occurs due to interfacial stresses associated with formation of hard and brittle heat affect zone. Laser cladding due to its advantages like minimal and controlled energy input can minimise the heat affected zone and minimise the formation of COx gases. Repair solutions with or without pre-heating were developed successfully.
Key Features
- Negligible porosity
- Crack free deposition
- No distortion
- Minimal heat affected region
Potential Applications
- Glass Mould Dies
- Cylinder Heads
- Cam Shafts
- Gear Boxes
- Heavy engineering equipment and machine beds
Intellectual Property Development Indices (IPDI)
- Performance and stability are validated at laboratory scale
- Prototypes are generated
- Field trials are underway
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