The Experts below are selected from a list of 18384 Experts worldwide ranked by ideXlab platform

Sylvain Marinel - One of the best experts on this subject based on the ideXlab platform.

  • Dielectric properties of flash spark plasma sintered BaTiO3 and CaCu3Ti4O12
    Scripta Materialia, 2019
    Co-Authors: Charles Manière, Guillaume Riquet, Sylvain Marinel
    Abstract:

    Flash Sintering is an approach allowing reducing the Sintering time to mere seconds. To improve the microstructures and the properties of flash sintered specimens, this process has been successfully adapted to pressure assisted Sintering such as the spark plasma Sintering. This work is the exploration of the potential of this ultra-rapid Sintering process for the improvement of the dielectric properties of well-known materials such as BaTiO 3 and CaCu 3 Ti 4 O 12. In particular, we focus on the potential improvement of the dielectric loss,

  • Dielectric properties of flash spark plasma sintered BaTiO3 and CaCu3Ti4O12
    Scripta Materialia, 2019
    Co-Authors: C. Manière, Guillaume Riquet, Sylvain Marinel
    Abstract:

    Flash Sintering is an approach allowing reducing the Sintering time to mere seconds. To improve the microstructures and the properties of flash sintered specimens, this process has been successfully adapted to pressure assisted Sintering such as the spark plasma Sintering. This work is the exploration of the potential of this ultra-rapid Sintering process for the improvement of the dielectric properties of well-known materials such as BaTiO3 and CaCu3Ti4O12. In particular, we focus on the potential improvement of the dielectric loss, colossal permittivity and microstructures of these materials after ~20 s Sintering and annealing. © 2019

Javier E. Garay - One of the best experts on this subject based on the ideXlab platform.

  • pressure less and current activated pressure assisted Sintering of titanium dual matrix composites effect of reinforcement particle size
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2009
    Co-Authors: V. V. Patel, Javier E. Garay, Ahmed Eldesouky, K Morsi
    Abstract:

    Abstract This paper investigates a microstructural design that can allow the tailorability of the properties of titanium–titanium boride composites. A powder processing sequence is used to allow the in situ growth of TiB whiskers in localized regions (of controlled size) of the microstructure leaving predominantly ductile titanium in between these reinforced regions. Both current-activated Pressure-Assisted Sintering (CAPAS) and pressure-less Sintering were used as high temperature consolidation processes for the powders. Superior composites in terms of consolidation, hardness and reaction completion were produced using CAPAS as opposed to pressure-less Sintering. For CAPAS processed materials, the size of the reinforced regions had a significant effect on the hardness of the composites, with values ranging from 652 to 777 VHN (a 19% difference).

  • Current-activated Pressure-Assisted Sintering (CAPAS) and nanoindentation mapping of dual matrix composites
    Journal of Materials Science, 2008
    Co-Authors: Khaled Morsi, V. V. Patel, K. S. Moon, Javier E. Garay
    Abstract:

    Titanium boride (TiB_w) whiskers are currently recognized as one of the most compatible reinforcements for titanium (Ti) that have positively affected its wear resistance and stiffness. The fracture toughness and ductility have, however, been reported to deteriorate at increased TiB_w volume fractions, mainly due to the interlocking of these brittle TiB whiskers. This article investigates the processing of dual matrix Ti–TiB_w composites, where microstructures are generated consisting of TiB_w–Ti composite regions separated by a ductile, predominantly Ti, outer matrix. This microstructural design has the potential to prevent the continuous TiB_w interlocking over the scale of the composite (at high TiB_w volume fractions), and promote improved toughness of the material. The processing of these unique composites using current-activated Pressure-Assisted Sintering (CAPAS) is discussed in this article. The effect of processing temperature on the microstructure and hardness of Ti–TiB_w dual matrix composites is also discussed, together with a simultaneous imaging and modulus-mapping nanoindentation technique used to characterize the composites

  • Processing of titanium–titanium boride dual matrix composites
    Journal of Materials Processing Technology, 2008
    Co-Authors: Khaled Morsi, V. V. Patel, Saeed Naraghi, Javier E. Garay
    Abstract:

    Abstract Discontinuously reinforced titanium (Ti)–titanium boride whisker (TiB w ) composites are emerging as strong candidate materials for advanced applications within the automotive, aerospace and defense industries. Although increasing TiB w volume fraction has been shown to significantly improve the specific stiffness and wear resistance of titanium, it is usually on the expense of fracture toughness and ductility especially at high volume fractions of reinforcements. This paper discusses the feasibility of processing Ti–TiB w dual matrix composites that could overcome these shortcomings, by generating composite microstructures consisting of TiB w –Ti composite regions separated by a ductile Ti matrix. This microstructural design has been previously shown to impart unique combinations of properties for other composites. However, the design has never been applied to Ti–TiB w in situ generated composites which require the consideration of new processing steps and the complication of a high-temperature in situ transformation to form TiB w . Two high-temperature powder consolidation methods were investigated (pressure-less Sintering and current-activated pressure assisted Sintering (CAPAS)). Other aspects investigated include the use of two different boron sources (titanium di-boride (TiB 2 ) and pure boron (B)) in addition to different composite particle sizes. Results show that pressure-less Sintering was neither effective at completely forming TiB w , nor generating high-density products. Full conversion to TiB w was however attained using CAPAS generating high-density Ti–TiB w dual matrix composites.

V. V. Patel - One of the best experts on this subject based on the ideXlab platform.

  • pressure less and current activated pressure assisted Sintering of titanium dual matrix composites effect of reinforcement particle size
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2009
    Co-Authors: V. V. Patel, Javier E. Garay, Ahmed Eldesouky, K Morsi
    Abstract:

    Abstract This paper investigates a microstructural design that can allow the tailorability of the properties of titanium–titanium boride composites. A powder processing sequence is used to allow the in situ growth of TiB whiskers in localized regions (of controlled size) of the microstructure leaving predominantly ductile titanium in between these reinforced regions. Both current-activated Pressure-Assisted Sintering (CAPAS) and pressure-less Sintering were used as high temperature consolidation processes for the powders. Superior composites in terms of consolidation, hardness and reaction completion were produced using CAPAS as opposed to pressure-less Sintering. For CAPAS processed materials, the size of the reinforced regions had a significant effect on the hardness of the composites, with values ranging from 652 to 777 VHN (a 19% difference).

  • Current-activated Pressure-Assisted Sintering (CAPAS) and nanoindentation mapping of dual matrix composites
    Journal of Materials Science, 2008
    Co-Authors: Khaled Morsi, V. V. Patel, K. S. Moon, Javier E. Garay
    Abstract:

    Titanium boride (TiB_w) whiskers are currently recognized as one of the most compatible reinforcements for titanium (Ti) that have positively affected its wear resistance and stiffness. The fracture toughness and ductility have, however, been reported to deteriorate at increased TiB_w volume fractions, mainly due to the interlocking of these brittle TiB whiskers. This article investigates the processing of dual matrix Ti–TiB_w composites, where microstructures are generated consisting of TiB_w–Ti composite regions separated by a ductile, predominantly Ti, outer matrix. This microstructural design has the potential to prevent the continuous TiB_w interlocking over the scale of the composite (at high TiB_w volume fractions), and promote improved toughness of the material. The processing of these unique composites using current-activated Pressure-Assisted Sintering (CAPAS) is discussed in this article. The effect of processing temperature on the microstructure and hardness of Ti–TiB_w dual matrix composites is also discussed, together with a simultaneous imaging and modulus-mapping nanoindentation technique used to characterize the composites

  • Processing of titanium–titanium boride dual matrix composites
    Journal of Materials Processing Technology, 2008
    Co-Authors: Khaled Morsi, V. V. Patel, Saeed Naraghi, Javier E. Garay
    Abstract:

    Abstract Discontinuously reinforced titanium (Ti)–titanium boride whisker (TiB w ) composites are emerging as strong candidate materials for advanced applications within the automotive, aerospace and defense industries. Although increasing TiB w volume fraction has been shown to significantly improve the specific stiffness and wear resistance of titanium, it is usually on the expense of fracture toughness and ductility especially at high volume fractions of reinforcements. This paper discusses the feasibility of processing Ti–TiB w dual matrix composites that could overcome these shortcomings, by generating composite microstructures consisting of TiB w –Ti composite regions separated by a ductile Ti matrix. This microstructural design has been previously shown to impart unique combinations of properties for other composites. However, the design has never been applied to Ti–TiB w in situ generated composites which require the consideration of new processing steps and the complication of a high-temperature in situ transformation to form TiB w . Two high-temperature powder consolidation methods were investigated (pressure-less Sintering and current-activated pressure assisted Sintering (CAPAS)). Other aspects investigated include the use of two different boron sources (titanium di-boride (TiB 2 ) and pure boron (B)) in addition to different composite particle sizes. Results show that pressure-less Sintering was neither effective at completely forming TiB w , nor generating high-density products. Full conversion to TiB w was however attained using CAPAS generating high-density Ti–TiB w dual matrix composites.

A. Maître - One of the best experts on this subject based on the ideXlab platform.

  • Identification of densification mechanisms of Pressure-Assisted Sintering: application to hot pressing and spark plasma Sintering of alumina
    Journal of Materials Science, 2015
    Co-Authors: G. Antou, P. Guyot, N. Pradeilles, M. Vandenhende, A. Maître
    Abstract:

    The identification of densification mechanism during hot uniaxial pressing is developed using an approach based on classical creep investigation. This approach is justified and generalised using continuum mechanics based Sintering models. The benefit of this approach is to directly determine the densification parameters from the analysis of shrinkage rates of the porous material, rather than to transpose the creep mechanisms identified for dense material at given thermomechanical conditions to the densification progress. The suggested approach is applied to compare the densification mechanisms involved at the initial stage of Sintering (i.e. for 60 % 

  • A Way to Identify Densification Mechanisms of Pressure-Assisted Sintering: Application to Hot Pressing and Spark Plasma Sintering of Alumina
    Journal of Materials Science, 2015
    Co-Authors: G. Antou, P. Guyot, N. Pradeilles, A. Maître
    Abstract:

    The identification of densification mechanism during hot uniaxial pressing is developed using an approach based on classical creep investigation. This approach is justified and generalised using continuum mechanics based Sintering models. The benefit of this approach is to directly determine the densification parameters from the analysis of shrinkage rates of the porous material, rather than to transpose the creep mechanisms identified for dense material at given thermomechanical conditions to the densification progress. The suggested approach is applied to compare the densification mechanisms involved at the initial stage of Sintering (i.e. for 60% < relative density < 75%) during Hot Pressing (HP) and Spark Plasma Sintering (SPS) of a submicrometric alpha-alumina powder. From the stress exponent and activation energy values, it is shown that the main mechanism involves grain boundary sliding accommodated by dislocation motion and particle fracture in both cases. However, it appears that, in SPS, the high heating rate could reduce the existence of surface diffusion phenomena at the beginning of the consolidation process, as suggested by the higher activation energy compared to the one determined for HP.

Charles Manière - One of the best experts on this subject based on the ideXlab platform.

  • Dielectric properties of flash spark plasma sintered BaTiO3 and CaCu3Ti4O12
    Scripta Materialia, 2019
    Co-Authors: Charles Manière, Guillaume Riquet, Sylvain Marinel
    Abstract:

    Flash Sintering is an approach allowing reducing the Sintering time to mere seconds. To improve the microstructures and the properties of flash sintered specimens, this process has been successfully adapted to pressure assisted Sintering such as the spark plasma Sintering. This work is the exploration of the potential of this ultra-rapid Sintering process for the improvement of the dielectric properties of well-known materials such as BaTiO 3 and CaCu 3 Ti 4 O 12. In particular, we focus on the potential improvement of the dielectric loss,

  • Spark plasma Sintering and complex shapes: The deformed interfaces approach
    Powder Technology, 2017
    Co-Authors: Charles Manière, Emmanuel Nigito, Yannick Beynet, Alicia Weibel, Lise Durand, Claude Estournès
    Abstract:

    Over the last few decades, the SPS technique has proven its benefits in terms of microstructure control, reduction of cycling time and a general stability of the results. However, to overcome the so-called “valley of death” between fundamental research and successful industrialization, the next step is to prove the ability of this technology to perform the total densification of highly complex shape samples. The elaboration of complex shapes with die compaction processes often present densification inhomogeneity because of the thickness differences of the sample. In this paper, we present a method to solve this problem with an approach we called the “deformed interfaces method” that uses sacrificial materials. This method can be generalized to all the pressure assisted Sintering techniques and allow a complete densification whatever the shape complexity of the part. This method is tested with different materials (Al, CoNiCrAlY, PMMA, Al2O3, 4Y-ZrO2) and shapes. To prove the effectiveness of this method on very high complex shapes, a 98% dense turbine blade shape has been made.