Centre for Advanced Ceramic Materials (CACM)

Overview

Pressure slip casting, a well known technique in practice for the table ware production has not yet been considered as a potential and productive method production for Advanced Ceramics. The PCS 100N (SAMA GmbH) has been worked upon to produce Advanced Ceramics products, initially that of Al2O3. The machine parameters have been stabilized and the optimization of slip preparation with local brands of Al2O3 has been successfully done to produce dense discs of sintered densities greater than 98%. The sintered discs of dia 70 mm and thickness >5 mm with above densities have been reproducibly produced on PCM to gain confidence. Reasonable expertise to prepare required polymer moulds suitable to be used on PCM to pressure cast desired shapes and dimensions has also been acquired during these trials. Polymer moulds prepared to pressure cast shapes like spools, solid spheres, one end closed tubes and successfully used on the PCM with Al2O3 slips. The work to make more complicated advanced ceramics like channelled (b/b) slabs, long cones, large slabs etc is in progress. Pressure casting of full solid spheres of Al2O3 with 60 mm dia and 60% green density is achieved successfully.

Key Features

• Highly productive with a possibility of almost 30 cycles/hr depending on the slip and product
• Yields 58%-60% green density and consistency is assured
• Easily up scalable to meet the industrial/commercial requirements
• Many complex shapes and structures can be easily pressure cast using aqueous slips
• Polymer moulds can be used to produce at least 15000-20000 cast cycles 
• Eco-friendly with minimum rejection (3% max.)
• Polymer mould fabrication can be a part of the PC technology
• Requires min man power. Can be automated if required

Potential Applications

• Manufacturing of advanced ceramics with complicated shapes, one end closed tubes, grinding media etc. with high productivity for commercialization

Intellectual Property Development Indices (IPDI)

• Technology for wear resistance alumina grinding balls demonstrated and undergoing field trials
• Polymer mould fabrication for required shapes established
• Pressure casting of alumina ceramic established for various shapes and dimensions 
• IPDI level: 6

Pressure casr and sintered to >98 density Al2O3 Solid spheres of dia 50 mm

Microstructure of the pressure Cast Al2O3 disc representing its fully dense nature

Major Patents / Publications

Major Patents*

• Inter Ceram 62 2013 (3) 221-223

Overview

Extrusion processing which involves the shaping of a visco-plastic formable paste through a specially designed die is the most commonly used technique used for the manufacture of honeycombs and tubes. The honeycomb extrusion is a complex process involving lateral flow of the dough followed by the knitting with adjacent cross section within the die the rheological properties of the dough play a major role. Because of the flexibility in tailoring, honeycombs can be engineered to exhibit a unique combination of mechanical and thermal properties for diversified thermo structural applications Rheological properties depends on a variety of factors such as the choice of the binder, the extent of solids loading in the dough, the particle characteristics of the ceramic powder used, etc.

Key Features

• Extrusion process for wide range of ceramic formulations
• Low expanding honeycomb cellular ceramics
• Thin walled porous and dense tubes
• Ram and Screw type extrusion processes
• Capability to design and fabricate in-house dies including for honeycombs
• Optimized heat treatment schedules based on the ceramic formulation
• Engineered structural, thermal and mechanical properties

Potential Applications

• Kiln Furniture and furnace fixtures
• Honeycomb substrates for catalysis 
• Energy absorption, conservation and generation
• Environmental protection 

Intellectual Property Development Indices (IPDI)

• Patented In-house honeycomb die fabrication technology in collaboration with Samara State University, Samara
• Ready to demonstrate extrusion process
• Extrusion technology for porous and dense tubes 

Screw type extrusion press

Extruded honeycomb with 324 CPSI

Overview

Engineered porosity plays an important role in achieving low thermal conductivity and hence on insulating performance. However, the loss of strength becomes an important disadvantage with increasing porosity. Quantity of porosity along with the tailored pore size becomes critical to choose an optimum as these properties conflicts each other. Methodologies are successfully developed to fabricate zirconia ceramics with optimum porosity and strength for thermal management applications.

Key Features

• Low thermal conductivity (<1W/m-K) 
• Highly stable cubic structure 
• Engineered porosity through fugitive pore formers 
• Moderate mechanical strength through optimum pore size distribution 
• Stability and durability in harsh environments 
• Capability for complex shaping

Potential Applications

• Self standing ceramic parts for insulation 
• High temperature insulation up to 1500oC

Intellectual Property Development Indices (IPDI)

• Key parameters demonstrated on coupon level 
• Formulation finalized and Heat treatment schedules optimized 
• Scale up trials are in progress

Zirconia porous disc ground to 65mm dia

Closed pores microstructure of zirconia porous disc

Overview

Ceramic foams are three-dimensional frame work with high porosity forming a tortuous system of interconnected cells and channels. Ceramic foams because of their inherent reticulated structure widely used as molten metal filters, catalyst supports, flame arrestors etc. Ceramic reticulated open cell foams are commonly processed by a polymer sponge processing.

Key Features

• Engineered pore densities, formulations, dimensions and shapes 
• Flexibility in process to achieve desired thermo- mechanical properties 
• Low pressure drop in combination with tortuous path 
• Light weight ceramics

Potential Applications

• Substrates for solar thermal applications 
• Bio-medical scaffolds 
• Catalyst substrates for pollution control 
• Hot gas and molten metal filters

Intellectual Property Development Indices (IPDI)

• Polymeric sponge processing is established for various ceramic formulations 
• Capability to develop the process based on the application

Digital photograph of ceramic foams

Digital photograph of ceramic foam

Major Patents / Publications

Major Publications

• Quasi-static compression behavior of nickel oxide, nickel oxide: zirconia, nickel:zirconia and nickel foams, Ceramics International, 42 (2016) 10572–10578 
• Development of Cordierite based Reticulated Foams with Improved Mechanical Properties for Porous Burner Applications, Transactions of Indian Ceramic Society (In press)

Overview

Chemical Vapour Deposition process developed using the reaction between zinc and hydrogen sulphide to produce stoichiometric zinc sulphide (ZnS). A technology of producing complex or simple shaped substrates for the CVD deposition depending on the target requirements is patented. Post processed CVD ZnS samples have shown close to theoretical values with respect to thermal, mechanical and transmission properties.

Key Features

• Theoretically dense  
• Near net shape
• High homogeneity
• Thickness building upto 10mm 

Potential Applications

• IR imaging
• Optical ceramics

Intellectual Property Development Indices (IPDI)

• IPDI level: 10 for ZnS

Photograph of Chemical Vapour Deposition unit

Digital photograph of ZnS discs

Major Patents / Publications

Major Publications

Overview

Gel casting process involves solidification of ceramic slurries by the free radical initiated polymerization of a chain forming monomer with a cross linking monomer in presence of a catalyst. Specific advantages such as high solid loading (50-55 vol %), instant solidification (15-60 min) and uniform green microstructure enabling green machining. However, acrylamide based gel casting process suffers from the serious drawback of being toxic as a result of which its use on a wide spread commercial scale has been limited. In view of this an environmentally benign nontoxic polymeric such as methyl cellulose, which undergo thermally induced gelation at temperatures in the range of 70-80°C has also experimented for shaping.

Key Features

• Acrylamide  based gelation through   polymerisation process
• Environmental friendly methyl cellulose based thermal gelation
• Flexibility in  polymer selection for the desired green strength 
• Near net complex shaping 
• Possibility of green machining of parts, if required

Potential Applications

• Shaping of near net shaped complex ceramic parts

Intellectual Property Development Indices (IPDI)

• Processing steps optimised 
• Capability to produce complex shapes

Digital photograph of gel cast sample

Digital photograph of gel cast sample

Overview

Ceramic powders encapsulated specially designed metallic can using an encapsulation welder under 10-3 Torr at elevated temperatures. The encapsulated capsule was subjected to direct consolidation by Hot Isostatic Pressing (HIP) at desired temperatures and pressures. Deformed capsule after HIP cycle was machined to release the dense compact. In a typical experiment with alumina ceramics samples was found to attain a density of 3.94 g/cc and a flexural strength of 310 MPa at a relatively low temperature of 1350oC in a single step of HIP consolidation.

Key Features

• Expertise  to design cans based on the part geometry
• Engineered  HIP parameters based on  formulations
• Single step densification process 
• Theoretical densities
• Scalable process 

Potential Applications

• Fabrication of  theoretically dense ceramic components
• Complex and simple geometries

Intellectual Property Development Indices (IPDI)

• Process established on a  laboratory level
• Scale-up and prototype module fabrication is in progress

SS HIP capsule with alumina powder and Densified alumina sample after HIPing and de-encapsulation

SEM microstructure of the thermally etched dense sample

Major Patents / Publications

Major Publications

• Vacuum Encapsulation of Sub-μm Alumina Powder and Densification by Direct Consolidation through Hot Isostatic Pressing, International Conference on Advance in Materials and Manufacturing, 8-10 December-2016.

Overview

Increasing concern on fossil fuel depletion has paved a way for the energy efficient and eco-friendly energy management technologies in various vital sectors. Porous Medium Combustion through reticulated foam structures is considered to be one of the feasible options which got explored extensively in the industrial and domestic applications. A wide variety of ceramic foams are developed and explored for porous burner applications.

Key Features

• Ceramic foam based Porous Combustion 
• High energy efficiency 
• Environmental friendly 
• Short start-up time

Potential Applications

• Energy efficient burning of gaseous fuels 
• Industrial radiant burners

Intellectual Property Development Indices (IPDI)

• Concept proved on a laboratory scale 
• Scale-up and prototype module fabrication in progress

Cordierite based porous burner

Cordierite open-cell foam (ARCI)

Major Patents / Publications

Major Publications

• Development of Cordierite based Reticulated Foams with Improved Mechanical Properties for Porous Burner Applications , Transactions of the Indian Ceramic Society-2016- In Press

Overview

Transparent ceramics, a new class of advanced functional materials, find diverse applications in strategic and civilian sectors owing to the unique combination of mechanical and transmission properties. Technological advancements in ceramic powder synthesis, shaping and sintering have made it possible to tailor the microstructural, mechanical and optical property relationships in case of advanced transparent ceramic materials. Transparent ceramic materials are classified broadly as visible, mid wave and long wave infrared regions.

Key Features

• Capability to fabricate polycrystalline transparent ceramic specimens  of transparent alumina, aluminium oxynitride (AlON), spinel (MgAl2O4) through slip casting and  Hot Isostatic Pressing
• Capability to fabricate transparent  zinc sulphide (ZnS) ceramics through Chemical Vapour Deposition (CVD) 
• Specific parameters depends on ceramic formulation

Potential Applications

• Dental  Ceramics and Artificial Gem Stones
• Solar Absorber Tubes and Lamp Envelops 
• IR sensor envelops
• High temperature Furnace windows

Intellectual Property Development Indices (IPDI)

• Process  steps optimised to achieve theoretical transmissions
• IPDI level
  • ZnS: 10
  • Magnesium aluminate spinel: 10

Digital photograph of Hot Isostatic Press

Transparent spinel blank

Major Patents / Publications

Major Publications

• Optical and mechanical properties of compaction and slip cast processed transparent polycrystalline spinel ceramics, Ceramics International 40 (2014) 5575–5581

Overview

Gel casting is a near net shape colloidal processing technique for ceramics which can be adapted to develop ceramic products having various size and shapes. This technique offers advantages of machining intricate shape ceramic parts in green condition. It is possible to tailor the properties of ceramics in terms of density, mechanical properties by tailoring the composition and processing parameters. ARCI has developed SiC, Si3N4 and SiAlON products in prototype scale with the help of gel casting process and successfully sintered the products without any warpage or defect.

Key Features

• Near-net processing of complex shapes. 
• Green machining
• Scalable to large size. 
• Cost effective. 

Potential Applications

• Non-oxide based crucibles for metallurgical industry.  
• Electromagnetic windows.  
• Cellular SiC product for solar receiver applications.  

Intellectual Property Development Indices (IPDI)

• Up-scaling is in progress for large size products. 

Non-oxide based green parts produced by gelcasting technique at ARCI

SEM micrographs of optimized SiAlON composition used in producing radomes prototype

Major Patents / Publications

Major Publications

• P. Barick, D.C. Jana and B.P. Saha, Load-dependent indentation behaviour of βSiAlON and αSilicon carbide, J. Adv. Ceram. 2, (2013), 185192.
• D. C. Jana, G. Sundararajan and K. Chattopadhyay, Effect of monomers content in enhancing solid-state densification of silicon carbide ceramics by aqueous gelcasting and pressureless sintering, Ceram. Inter., 43 (2017), 4852-4857.
• K. M. Reddy and B. P. Saha, Microstructure-property correlation of porous β-SiAlON ceramics, J. Alloy. Comp., 779 (2019), 590-598.

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  

SEM micrograph of spray-freeze-dried RTP SiC granules

SiC inserts produced by use of ARCI produced RTP SiC granules

Major Patents / Publications

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

Overview

Silicon carbide (SiC) is one of the most attractive ceramic materials because of its excellent mechanical properties such as high strength, moderate toughness, and high wear and oxidation resistance, and strength retention at elevated temperature. ARCI has the expertise to manufacture SiC parts with various size and shapes by pressureless sintering using solid-state or liquid phase sintering additives and also by hot pressing technique. SiC parts of complex geometry can also be manufactured through machining at the green stage using 5-axis CNC machine. Dimensional accuracy can also be achieved on sintered SiC parts by final shaping with the help of sophisticated ultrasonic machining.

Key Features

• Tuneable density and other thermo-mechanical properties.  
• Flexibility in producing SiC parts incorporating solid-state or liquid phase sintering additives. 
• Capable to produce SiC components up to 750 mm diameter. 
• SiC parts with critical can be manufactured. 

Potential Applications

• Mechanical seals particularly for corrosive environment. 
• Impact and abrasion resistance parts. 
• Light-weight structural parts for aerospace applications. 
• Impact and wear resistant parts. 

Intellectual Property Development Indices (IPDI)

• The technology has been validated for production of various size and shape SiC parts by pressureless sintering and available for technology transfer.

Complex shaped sintered SiC parts for aerospace applications

3-axis ultrasonic machining facility

Major Patents / Publications

Major Publications

• P. Barick, D. C. Jana and B.P. Saha, Load-dependent indentation behaviour of βSiAlON and αSilicon carbide, Journal of Advanced Ceramics, 2, (2013), 185192.
• S. V. A. Raj, D. C. Jana, P. Barick and B. P. Saha, Microstructure Evolution in Densification of SiC Ceramics by Aluminium Vapour Infiltration and Investigation of Mechanical Properties, Ceram. Inter., 44 (2018), 9221-9226
• D. C. Jana, P. Barick and B. P. Saha, Effect of Sintering Temperature on Density and Mechanical Properties of Solid-State Sintered Silicon Carbide Ceramics and Evaluation of Failure Origin, J. Mater. Eng. Perform., 27 (2018), 2960-2966.
• D. C. Jana, G. Sundararajan and K. Chattopadhyay, Effective activation energy for the solid-state sintering of silicon carbide ceramics, Met. Mater. Trans. A, Vol 49 A (2018), 5599-5606.

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.

Chemical vapour deposition (CVD) facility

SEM micrograph for polished CVD SiC coating

Overview

SiC tubes have emerged as potential candidate material in the area of concentrated solar power generation, heat exchangers for recovery of heat from industrial waste, fuel cladding in nuclear reactors because of superior thermos-mechanical properties, high thermal conductivity, resistance to chemical attack and nuclear radiation. ARCI has developed the process for producing SiC tube by extrusion as well as cold iso-static pressing technique followed by sintering.

Key Features

• Extrusion press is capable of producing long tubes of different diameter and wall thickness.  
• High production rate.
• Process flexibility to produce dense and porous SiC tubes. 

Potential Applications

• Tubular solar receiver in CSP technology.
• Heat exchanger.
• Nuclear fuel cladding tubes.  
• Support tubes in membrane separation. 

Intellectual Property Development Indices (IPDI)

• SiC tubes produced by both extrusion and cold-isostatic pressing have been produced and properties tubes are being evaluated.  

Extrusion of SiC tubes

700 mm long sintered SiC tubes

Major Patents / Publications

Major Publications

• S. Mubina, A. K. Khanra and B. P. Saha, Processing of sintered and CVD coated SiC/CNFs thin composite tubes, Mater. Chem. Phys., 220 (2018), 225-232.

Overview

Sodium beta alumina has been late seen as one of the highly potential candidates for battery and other electrolyte based applications due to firstly its high levels of sodium ion conductivity and secondly for the availability and the low price of the raw materials required to prepare the desired composition. Easier to make at the lab level to demonstrate the technical features but its physical and chemical properties like sensitive to humidity, water, high sintering temperatures, sodium evapouration, low densities achieved, limited shelf life and limitations in scaling up of powder production etc., have made it difficult to get absorbed by the industry for real device applications. ARCI has taken up two projects to develop sintered shapes of Sodium bet alumina for two entirely different applications where the prime feature exploited would be its ionic conductivity. Production of kilograms of the powder reproducibly and maintaining its phase purity by inert storing has been established. Fabrication and successful firing overcoming the issue of sodium evaporation to obtain tube and container shapes is achieved. Field trails and number production is due and in progress.

Key Features

• Sodium beta alumina powder synthesis established in kgs level via solid state routes 
• Sodium evaporation issues solved
• Desired densities (>94%) achieved at 1650-1700 Deg C
• Shaping issues resolved- tubes, containers prepared through casting /CIP techniques
• Storage in inert way safeguarding the phase purity is established
•  Making of shapes in numbers is in progress

Potential Applications

• Sodium ion based ionic conductor- A good electrolyte
• High energy battery applications
• Selective separation techniques based on its ionic conductivity

Intellectual Property Development Indices (IPDI)

• Performance and stability are validated at laboratory scale
• Scale-up and prototype module fabrication underway

A typical one end tube of sintered Sodium beta alumina ready for testing

Phase purity as seen by XRD

Overview

Solid oxide fuel cells (SOFCs) are used for a wide range of applications including power generation, automobile etc. Planar SOFC configurations appear superior to other form, like tubular based onsuperior power density and efficiency. A major issue in planar SOFCs is the requirement that hermetic sealing must be formed between the solid electrolyte and/or the ceramic anode with the metallic interconnect in order to prevent fuel - oxidant mixing and to provide electrical insulation. The wide range of thermal expansion characteristics and the thermal stability advantages of glass based sealant (or glass-ceramics) are important factors in sealing. To ascertainacceptable lifetime, interfacial reactions and diffusion of both metallic and glass species should be minimized. Glass based sealant capable to form rigid seal between the interconnect and other SOFC parts, which in turn reduce the leak rate within acceptable limit.

Key Features

• Tuneable compositions and properties (e.g. CTE, resistance to reaction with adjacent part).
• Wide range of glass compositions for suitability as sealant
• Simplicity in makingglass frits, powders and subsequently sealing paste.
• Compatibility with the SOFC stack components such as cathode, anode and interconnect
• Application temperature: 800-850⁰c
• Ability to self-heal the crack (if any) in seal during operation

Potential Applications

• Sealant for SOFC stack.

Intellectual Property Development Indices (IPDI)

Water quenched glass frits

Annealed glass samples

Overview

SiC tubes have emerged as potential candidate material in the area of concentrated solar power generation, heat exchangers for recovery of heat from industrial waste, fuel cladding in nuclear reactors because of superior thermos-mechanical properties, high thermal conductivity, resistance to chemical attack and nuclear radiation. ARCI has developed the process for producing SiC tube by extrusion as well as cold iso-static pressing technique followed by sintering.

Key Features

• Extrusion press is capable of producing long tubes of different diameter and wall thickness.
• High production rate.
• Process flexibility to produce dense and porous SiC tubes.

Potential Applications

• Tubular solar receiver in CSP technology.
• Heat exchanger.
• Nuclear fuel cladding tubes.
• Support tubes in membrane separation.

Intellectual Property Development Indices (IPDI)

• SiC tubes produced by both extrusion and cold-isostatic pressing have been produced and properties tubes are being evaluated.

Extrusion of SiC tubes

700 mm long sintered SiC tubes

Major Patents / Publications

Major Publications

• S. Mubina, A. K. Khanra and B. P. Saha, Processing of sintered and CVD coated SiC/CNFs thin composite tubes, Mater. Chem. Phys., 220 (2018), 225-232.
• S. Mubina, M. Ilaiyaraja, A.K. Khanra, B. P. Saha, Fabrication and microstructure analysis of continuous C fibers reinforced SiC-CNTs hybrid composite tubes, Materials and Manufacturing Processes, 36 (2021) 292-300.
• S. Mubina, P. S. Phani, A. K. Khanra, B. P. Saha, A nanoindentation based study to evaluate the effect of carbon nanofibers on the mechanical properties of SiC composites, Journal of Composite Interfaces, 2020, 1-18, DOI: 10.1080/09276440.2020.1780555
• S. Mubina, A. Khanra, B. P. Saha, Enhancement of oxidation resistance of CVD SiC coated Cf/C-SiC hybrid composite tubes processed through Si-infiltration, Journal of Alloys and Compounds, Journal of Alloys and Compounds, volume 826. 154107,DOI:10.1016/j.jallcom.2020.154107.
• S.Mubina, A. Khanra, B. P. Saha, Optimization of processing parameters, physical and mechanical properties of SiC – CNF composites using Taguchi approach, Material Today Proceedings, 18 (2019) 75300-5308

Overview

Ready-to-press non oxide ceramic granules such as silicon carbide (SiC) and SiAlON are 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 or Si3N4-based composite powders, 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 non oxide ceramic compacts with high density, defect free homogenous microstructure. The sintered products thus produced exhibit superior properties than conventionally produced powders. 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 isin progress

SEM micrograph of spray-freeze-dried RTP SiC granules

SiC inserts produced by use of ARCI produced RTP SiC granules

Major Patents / Publications

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.
• P. Barick, B.V. Shalini, M. Srinivas, D. C. Jana, and B. P. Saha, A facile route for producing spherical granules comprising water reactive aluminium nitride added composite powders, Adv. Powder Technol., 31 (2020) 2119-2127.

Overview

Theoretically dense SiC coating processed by chemical vapour deposition (CVD) exhibits superior physical, mechanical, thermaland 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 CVDsystem 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 onvarious 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.

Chemical vapour deposition (CVD) facility

SEM micrograph for polished CVD SiC coating

Major Patents / Publications

Major Publications

• D. C. Jana and B. P Saha, Silicon carbide-based lightweight mirror blanks for space optics applications. In: Y. Mahajan and R. Johnson (Eds) Handbook of Advanced Ceramics and Composites, First Edition, Springer Nature Switzerland AG, 2020, pp. 1135-1163.

Overview

Silicon carbide (SiC) is one of the most attractive ceramic materials because of its excellent mechanical properties such as high strength, moderate toughness, and high wear and oxidation resistance, and strength retention at elevated temperature. ARCI has the expertise to manufacture SiC parts with various size and shapes by pressureless sintering using solid-state or liquid phase sintering additives and also by hot pressing technique. SiC parts of complex geometry can also be manufactured through machining at the green stage using 5-axis CNC machine. Dimensional accuracy can also be achieved on sintered SiC parts by final shaping with the help of sophisticated ultrasonic machining.

Key Features

• Tuneable density and other thermo-mechanical properties.
• Flexibility in producing SiC parts incorporating solid-state or liquid phase sintering additives.
• Capable to produce SiC components up to 750 mm diameter.
• SiC parts with critical can be manufactured.

Potential Applications

• Mechanical seals particularly for corrosive environment.
• Impact and abrasion resistance parts.
• Light-weight structural parts for aerospace applications.
• Impact and wear resistant parts.

Intellectual Property Development Indices (IPDI)

• The technology has been validated for production of various size and shape SiC parts by pressureless sintering and available for technology transfer.

Complex shaped sintered SiC parts for aerospace applications

Major Patents / Publications

Major Publications

• P. Barick, D. C. Jana and B.P. Saha, Load-dependent indentation behaviour of β­SiAlON and α­ Silicon carbide, Journal of Advanced Ceramics, 2, (2013), 185­192.
• S. V. A. Raj, D. C. Jana, P. Barick and B. P. Saha, Microstructure Evolution in Densification of SiC Ceramics by Aluminium Vapour Infiltration and Investigation of Mechanical Properties, Ceram. Inter., 44 (2018), 9221-9226
• D. C. Jana, P. Barick and B. P. Saha, Effect of Sintering Temperature on Density and Mechanical Properties of Solid-State Sintered Silicon Carbide Ceramics and Evaluation of Failure Origin, J. Mater. Eng. Perform.,27 (2018), 2960-2966.
• D. C. Jana,G. Sundararajan and K. Chattopadhyay, Effective activation energy for the solid-state sintering of silicon carbide ceramics, Met. Mater. Trans. A, Vol 49 A (2018), 5599-5606.