Interface and Microstructure Development in Carbon/Carbon Composites

R.B. Mathur,O.P. Bahl,T.L. Dhami,S.K. Chauhan,S.R. Dhakate,B. Rand 한국탄소학회 2004 Carbon Letters Vol.5 No.2

Performance of carbon-carbon composites is known to be influenced by the fibre matrix interactions. The present investigation was undertaken to ascertain the development of microstructure in such composites when carbon fibres possessing different surface energies (T-300, HM-35, P120 and Dialed 1370) and pitch matrices with different characteristics (Coal tar pitch SP110℃ and mesophase pitch SP285℃) are used as precursor materials. These composites were subjected to two different heat treatment temperatures of 1000℃ and 2600℃. Quite interesting changes in the crystalline parameters as well as the matrix microstructure are observed and attempt has been made to correlate these observations with the fibre matrix interactions.

Interface and Microstructure Development in Carbon/Carbon Composites

Mathur, R.B.,Bahl, O.P.,Dhami, T.L.,Chauhan, S.K.,Dhakate, S.R.,Rand, B. Korean Carbon Society 2004 Carbon Letters Vol.5 No.2

Performance of carbon-carbon composites is known to be influenced by the fibre matrix interactions. The present investigation was undertaken to ascertain the development of microstructure in such composites when carbon fibres possessing different surface energies (T-300, HM-35, P120 and Dialed 1370) and pitch matrices with different characteristics (Coal tar pitch $SP110^{\circ}C$ and mesophase pitch $SP285^{\circ}C$) are used as precursor materials. These composites were subjected to two different heat treatment temperatures of $1000^{\circ}C$ and $2600^{\circ}C$. Quite interesting changes in the crystalline parameters as well as the matrix microstructure are observed and attempt has been made to correlate these observations with the fibre matrix interactions.

Challenges in Carbon/Carbon Composites Technologies

T.L. Dhami,O.P. Bahl 한국탄소학회 2005 Carbon Letters Vol.6 No.3

Carbon/Carbon Composites due to their far superior thermo-mechanical properties are used in a number of demanding applications. However, the material still is used only in specific high tech applications with few exceptions in general industrial applications. The material is extremely expensive and the major challenge is to reduce its cost. Various innovative processing routes are outlined to reduce the cost of processing.

Challenges in Carbon/Carbon Composites Technologies

Dhami, T.L.,Bahl, O.P. Korean Carbon Society 2005 Carbon Letters Vol.6 No.3

Carbon/Carbon Composites due to their far superior thermo-mechanical properties are used in a number of demanding applications. However, the material still is used only in specific high tech applications with few exceptions in general industrial applications. The material is extremely expensive and the major challenge is to reduce its cost. Various innovative processing routes are outlined to reduce the cost of processing.

Controlling the Hardness and Tribological Behaviour of Non-asbestos Brake Lining Materials for Automobiles

Mathur, R.B.,Thiyagarajan, P.,Dhami, T.L. Korean Carbon Society 2004 Carbon Letters Vol.5 No.1

In spite of unparalleled combination of essential material properties for brake linings and clutch facings, replacement for asbestos is seriously called for since it is a health hazard. Once asbestos is replaced with other material then composition and properties of brake pad changes. In certain cases hardness of the material may be high enough to affect the rotor material. In this study, hardness of the brake pad has been controlled using suitable reinforcement materials like glass, carbon and Kevlar pulp. Brake pad formulations were made using CNSL (cashew net shell liquid) modified phenolic resin as a binder, graphite or cashew dust as a friction modifier and barium sulphate, talc and wollastonite as fillers. Influence of each component on the hardness value has been studied and a proper formulation has been arrived at to obtain hardness values around 35 on Scleroscopic scale. Friction and wear properties of the respective brake pad materials have been measured on a dynamometer and their performance was evaluated.

Role of Interface on the Development of Microstructure in Carbon-Carbon Composites

Dhakate, S.R.,Mathur, R.B.,Dhami, T.L.,Chauhan, S.K. Korean Carbon Society 2002 Carbon Letters Vol.3 No.4

Microstructure plays an important role in controlling the fracture behaviour of carbon-carbon composites and hence their mechanical properties. In the present study effort was made to understand how the different interfaces (fiber/matrix interactions) influence the development of microstructure of the matrix as well as that of carbon fibers as the heat treatment temperature of the carbon-carbon composites is raised. Three different grades of PAN based carbon fibres were selected to offer different surface characteristics. It is observed that in case of high-strength carbon fiber based carbon-carbon composites, not only the matrix microstructure is different but the texture of carbon fiber changes from isotropic to anisotropic after HTT to $2600^{\circ}C$. However, in case of intermediate and high modulus carbon fiber based carbon-carbon composites, the carbon fiber texture remains nearly isotropic at $2600^{\circ}C$ because of relatively weak fiber-matrix interactions.

Thermomechanical Properties of Carbon Fibres and Graphite Powder Reinforced Asbestos Free Brake Pad Composite Material

Thiyagarajan, P.,Mathur, R.B.,Dhami, T.L. Korean Carbon Society 2003 Carbon Letters Vol.4 No.3

Asbestos is being replaced throughout the world among friction materials because of its carcinogenic nature. This has raised an important issue of heat dissipation in the non-asbestos brake pad materials being developed for automobiles etc. It has been found that two of the components i.e. carbon fibres as reinforcement and graphite powder as friction modifier, in the brake pad material, can playa vital role in this direction. The study reports the influence of these modifications on the thermal properties like coefficient of thermal expansion (CTE) and thermal conductivity along with the mechanical properties of nonasbestos brake pad composite samples developed in the laboratory.

A Novel Route to Realise High Degree of Graphitization in Carbon-carbon Composites Derived from Hard Carbons

Mathur, R.B.,Bahl, O.P.,Dhami, T.L.,Chauhan, S.K. Korean Carbon Society 2003 Carbon Letters Vol.4 No.3

Carbon/carbon composites were developed using PAN based carbon fibres and phenolic resin as matrix in different volume fractions and heat treated to temperatures between $1000^{\circ}C$ to $2500^{\circ}C$. Although both the starting precursors are nongraphitizing hard carbons individually, their composites lead to very interesting properties e.g. x-ray diffractograms show the development of graphitic phase for composites having fibre volume fractions of 30~40%. Consequently the electrical resistivity of such composites reaches a value of $0.8\;m{\Omega}cm$, very close to highly graphitic material. However, it was found that by increasing the fibre volume fraction to 50~60%, the trend is reversed. Optical microscopy of the composites also reveals the development of strong columnar type microstructure at the fibre (matrix interface due to stress graphitization of the matrix. The study forcasts a unique possibility of producing high thermal conductivity carbon/carbon composites starting with carbon fibres in the chopped form only.

Thermomechanical Properties of Carbon Fibres and Graphite Powder Reinforced Asbestos Free Brake Pad Composite Material

P. Thiyagarajan,R.B. Mathur,T.L. Dhami 한국탄소학회 2003 Carbon Letters Vol.4 No.3

Asbestos is being replaced throughout the world among friction materials because of its carcinogenic nature. This has raised an important issue of heat dissipation in the non-asbestos brake pad materials being developed for automobiles etc. It has been found that two of the components i.e. carbon fibres as reinforcement and graphite powder as friction modifier, in the brake pad material, can playa vital role in this direction. The study reports the influence of these modifications on the thermal properties like coefficient of thermal expansion (CTE) and thermal conductivity along with the mechanical properties of nonasbestos brake pad composite samples developed in the laboratory.

A Novel Route to Realise High Degree of Graphitization in Carbon-carbon Composites Derived from Hard Carbons

R.B. Mathur,O.P. Bahl,T.L. Dhami,S.K. Chauhan 한국탄소학회 2003 Carbon Letters Vol.4 No.3

Carbon/carbon composites were developed using PAN based carbon fibres and phenolic resin as matrix in different volume fractions and heat treated to temperatures between 1000℃ to 2500℃. Although both the starting precursors are nongraphitizing hard carbons individually, their composites lead to very interesting properties e.g. x-ray diffractograms show the development of graphitic phase for composites having fibre volume fractions of 30~40%. Consequently the electrical resistivity of such composites reaches a value of 0.8 mΩcm, very close to highly graphitic material. However, it was found that by increasing the fibre volume fraction to 50~60%, the trend is reversed. Optical microscopy of the composites also reveals the development of strong columnar type microstructure at the fibre (matrix interface due to stress graphitization of the matrix. The study forcasts a unique possibility of producing high thermal conductivity carbon/carbon composites starting with carbon fibres in the chopped form only.