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254. Comparison between progressive graphitization and phase-change graphitization (natural graphite formation)
Abstracts
153
the untreated wood modified by thinning down of cellular walls and macroscopic contraction of the entire sample.
can be reduced to preserve the bone less injured during implantation.
254. Comparison between progressive grapbitization and phase-change graphitization (natural graphite formation) M. Bonijoly, M. Oberlin and A. Oberlin (Labor&ire Marcel Mathieu, ER 131 du CNRS, EUR Sciences, 45046, Orleans Cedex, France). Thermal treatment of soft carbons leads to progressive graphitization. It is improbable in nature since it requires a high activation energy. Graphite formation is thus attributed to shear stresses caused by pressure and geothermal gradient as in high pressure-high temperature experiments. A thermally stable carbon appears first (partially graphitized), then graphite.
258. High-temperature dffatometric studies of carbon materials Z. Stompel, Z. Robak (Institute for Chemical Processing of Coal, 41-803 Zabrze, Poland and K. Skoczkowski, J. Gonsior and J. Lukoszek (Zaklady Eiektrod Weglowych, 47-100 Raciborz, Poland). Dilatation and shrinkage of cokes, particularly electrode cokes, as well as artificial carbons as blocks and electrodes on heating and cooling play an important role in their use. High temperature (over 1000°C)dimensional changes of these materials are of particular interest. Using a high temperature dilatometer we have determined L/L,, of large amount of carbons and graphites in the temperature range up to 1600°C.The “thermal history” of the sample and physical changes that occur during calcination could be studied by means of this technic.
W.
MECHANICAL
ANDTHERMALPROPERTIRS
255. Measurement of crack propagation velocity in nuclear graphite T. Maruyama, S. Ishiyama and H. Suzuki (Research
259. An investigation of tbe impact propertiesof graphite M. Birch and J. E. Brocklehurst (Graphite and
Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Ohokayama, Meguro-ku, Tokyo 152, Japan). An ultrasonic nondestructive test procedure has
Ceramics Technology Group, Springfields Nuclear Power Development Laboratories, UKAEA, Salwick, Preston, Lancashire, England). A study of the impact failure of
been applied to measure crack propagation velocity in nuclear graphites. A compact tension type specimen was used and ethos from crack was monitored. The crack length was determined in terms of ultrasonic echo signal and transducer position. The technique was applied to measure slow crack growth due to fatigue cycles.
graphite is reported which includes an investigation of the effect of specimen size and geometry together with a comparison of various grades of polycrystalline graphite covering a range of static strengths. Measurements of impact force, contact-time and specimen displacement are compared for these different materials.
256. The mechanical strength of needle coke grains in relation to coke structure H. Pauls, G. Pietzka and H. Tillmanns (Sign’ Elektro-
260. Thermal and mechanical propertiesof grapbnol N3M graphite (mantech material) Robert J. Edwards (Naval Surface Weapons Center, Silver Spring, MD 20910) and H. Stuart Starrett
graphit GmbH, Stroofstr. 27, D 6230 Frankfurt 80, Germany). Mechanical strength of needle cokes depends on
the porosity and coefficient of thermal expansion, both related to the microscopic structure and orientation within the coke grains. Two simple methods for testing crushing and abrasion resistance were used to confirm these considerations, in combination with characterization by CTE-measurements, bulk density and microscopic observation. 257. Dynamic impact strength tests of sflicon-carbide/graphitedouble cup prosthesis W. Hiiettner and G. Keuscher (Schunk & Ebe GmbH, Giessen, FRG) and K. Mueller (Staatiche Materialprofungsanstalt, TH Darmstadt, FRG). Clinical tests of double cup prosthesis fabricated by silicon-carbide/graphite composites have been started. Before implantation a special impact test was set up to measure the impact resistance of Sic/C double cup prosthesis. The tests were performed to simulate the real behaviour under critical movements. It was found, that the dynamic impact strength of the prosthesis exceeds 60 times of the average human weight; ten times is assumed to be the maximal acting load. The results show, that no failure of the prosthesis should occur during lifetime of the patient. As a further result the wall thickness of the prosthesis
(Southern Research
Institute, Birmingham,
AL 35205).
GRAPHNOL-N3M is a bulk graphite recently developed for advanced thermostructural applications in aerospace thermal protection systems. When compared to state-ofthe-art graphites such as ATJ-S, 994 and CMT, the N3M material has exhibited a significant increase in thermal stress resistance, and it also has a low ablation rate and exhibits high resistance to erosion from particle impacts. The laboratory scale process has been adapted to a production facility and nondestructive, mechanical and thermal evaluations have been performed on 5 in. dia. by 9 in. long billets. N3M properties will be compared with state-of-the-art materials. 261. Effect of flaw size on tbe tensile strain-to-failure of grapbnol N3M graphite H. S. Starrett (Southern Research Institute, Birmingham, AL 35205) and R. J. Edwards (Naval Surface Weapons Center, Silver Spring, MD20910). A curve of tensile strain-to-failure versus flaw size has been established for N3M graphite. The curve includes the influence of both edge and internal flaws ranging in size from 0.15 in. for edge flaws to 0.080 in. for internal flaws. The difference between the effect of the edge and internal flaws on the measured tensile strains-to-failure can be
153
the untreated wood modified by thinning down of cellular walls and macroscopic contraction of the entire sample.
can be reduced to preserve the bone less injured during implantation.
254. Comparison between progressive grapbitization and phase-change graphitization (natural graphite formation) M. Bonijoly, M. Oberlin and A. Oberlin (Labor&ire Marcel Mathieu, ER 131 du CNRS, EUR Sciences, 45046, Orleans Cedex, France). Thermal treatment of soft carbons leads to progressive graphitization. It is improbable in nature since it requires a high activation energy. Graphite formation is thus attributed to shear stresses caused by pressure and geothermal gradient as in high pressure-high temperature experiments. A thermally stable carbon appears first (partially graphitized), then graphite.
258. High-temperature dffatometric studies of carbon materials Z. Stompel, Z. Robak (Institute for Chemical Processing of Coal, 41-803 Zabrze, Poland and K. Skoczkowski, J. Gonsior and J. Lukoszek (Zaklady Eiektrod Weglowych, 47-100 Raciborz, Poland). Dilatation and shrinkage of cokes, particularly electrode cokes, as well as artificial carbons as blocks and electrodes on heating and cooling play an important role in their use. High temperature (over 1000°C)dimensional changes of these materials are of particular interest. Using a high temperature dilatometer we have determined L/L,, of large amount of carbons and graphites in the temperature range up to 1600°C.The “thermal history” of the sample and physical changes that occur during calcination could be studied by means of this technic.
W.
MECHANICAL
ANDTHERMALPROPERTIRS
255. Measurement of crack propagation velocity in nuclear graphite T. Maruyama, S. Ishiyama and H. Suzuki (Research
259. An investigation of tbe impact propertiesof graphite M. Birch and J. E. Brocklehurst (Graphite and
Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Ohokayama, Meguro-ku, Tokyo 152, Japan). An ultrasonic nondestructive test procedure has
Ceramics Technology Group, Springfields Nuclear Power Development Laboratories, UKAEA, Salwick, Preston, Lancashire, England). A study of the impact failure of
been applied to measure crack propagation velocity in nuclear graphites. A compact tension type specimen was used and ethos from crack was monitored. The crack length was determined in terms of ultrasonic echo signal and transducer position. The technique was applied to measure slow crack growth due to fatigue cycles.
graphite is reported which includes an investigation of the effect of specimen size and geometry together with a comparison of various grades of polycrystalline graphite covering a range of static strengths. Measurements of impact force, contact-time and specimen displacement are compared for these different materials.
256. The mechanical strength of needle coke grains in relation to coke structure H. Pauls, G. Pietzka and H. Tillmanns (Sign’ Elektro-
260. Thermal and mechanical propertiesof grapbnol N3M graphite (mantech material) Robert J. Edwards (Naval Surface Weapons Center, Silver Spring, MD 20910) and H. Stuart Starrett
graphit GmbH, Stroofstr. 27, D 6230 Frankfurt 80, Germany). Mechanical strength of needle cokes depends on
the porosity and coefficient of thermal expansion, both related to the microscopic structure and orientation within the coke grains. Two simple methods for testing crushing and abrasion resistance were used to confirm these considerations, in combination with characterization by CTE-measurements, bulk density and microscopic observation. 257. Dynamic impact strength tests of sflicon-carbide/graphitedouble cup prosthesis W. Hiiettner and G. Keuscher (Schunk & Ebe GmbH, Giessen, FRG) and K. Mueller (Staatiche Materialprofungsanstalt, TH Darmstadt, FRG). Clinical tests of double cup prosthesis fabricated by silicon-carbide/graphite composites have been started. Before implantation a special impact test was set up to measure the impact resistance of Sic/C double cup prosthesis. The tests were performed to simulate the real behaviour under critical movements. It was found, that the dynamic impact strength of the prosthesis exceeds 60 times of the average human weight; ten times is assumed to be the maximal acting load. The results show, that no failure of the prosthesis should occur during lifetime of the patient. As a further result the wall thickness of the prosthesis
(Southern Research
Institute, Birmingham,
AL 35205).
GRAPHNOL-N3M is a bulk graphite recently developed for advanced thermostructural applications in aerospace thermal protection systems. When compared to state-ofthe-art graphites such as ATJ-S, 994 and CMT, the N3M material has exhibited a significant increase in thermal stress resistance, and it also has a low ablation rate and exhibits high resistance to erosion from particle impacts. The laboratory scale process has been adapted to a production facility and nondestructive, mechanical and thermal evaluations have been performed on 5 in. dia. by 9 in. long billets. N3M properties will be compared with state-of-the-art materials. 261. Effect of flaw size on tbe tensile strain-to-failure of grapbnol N3M graphite H. S. Starrett (Southern Research Institute, Birmingham, AL 35205) and R. J. Edwards (Naval Surface Weapons Center, Silver Spring, MD20910). A curve of tensile strain-to-failure versus flaw size has been established for N3M graphite. The curve includes the influence of both edge and internal flaws ranging in size from 0.15 in. for edge flaws to 0.080 in. for internal flaws. The difference between the effect of the edge and internal flaws on the measured tensile strains-to-failure can be