JOURNAL OF MATERIALS SCIENCE 40(2005)5483-5490 Robust design and manufacturing of ceramic laminates with controlled thermal residual stresses for enhanced toughness NINA ORLOVSKAYA Drexe/ University, 3141 Chestnut St. Philadelphia, PA 19104, USA E-mail: orlovsk @drexel.edu MYKOLA LUGOVY, VLADIMIR SUBBOTIN, OLEKSANDR RADCHENKO Institute for Problems of materials science. 3 Krzhizhanovskii st. 03, Kiev. Ukraine JANE ADAMS Army Research Laboratory, Aberdeen Proving Ground, MD 2 1005, USA MUNJAL CHHEDA. JAMES SHIH Ceradyne Inc, 3169 Redhill Ave, Costa Mesa, CA 92626, USA JAG SANKAR SERGEY YARMOLENKO North Carolina a&T State University, 1601 E Market St, Greensboro, NC 27411, USA Boron carbide-silicon carbide ceramic composites are very promising armor materials because they are intrinsically very hard. However, their fracture toughness is not very high. Their ballistic performance could be significantly increased if the brittleness of these materials could be decreased. Here we report development of boron carbide-silicon carbide layered ceramics with controlled compressive and tensile stresses in separate layers Such B4C-SiC laminates with strong interfaces can provide high apparent fracture toughness and damage tolerance along with high protection capabilities The theory of heterogeneous layered systems was used to develop optimal design parameters allowing the evaluation and maximization of apparent fracture toughness. The layered composites were designed in a way to achieve high compressive residual stresses in thin B4c-sic based layers and low tensile residuals stresses in thick B4C layers. The residual stresses were controlled by the phase composition of layers and the layers hickness. The estimated apparent fracture toughness was calculated for both three layered and nine layered composites. B4 C-30 wt%SiC/B4C laminates were made based on the optimized design for high apparent fracture toughness. Processing of laminates involved preprocessing of powders, forming green tapes and hot pressing Work is in progress to measure fracture toughness of laminates as well as their strength, hardness and the ballistic performance. C 2005 Springer Science Business Media, Inc. 1. Introduction method to control cracks and brittle fracture by defied Ceramics offer a number of attractive properties. These tion, microcracking, or internal stresses [5-7].Lami include high specific stiffness, high specific strengths, nates with strong interfaces, combined with excellent low thermal conductivities, and chemical inertness in fracture toughness and damage tolerance, can poten ny environments. Ceramics and ceramic compos- tially provide the highest ballistic performance. The due to low density, superior hardness, and compres- is to control the level of residual stresses in the indi- sive strength values relative to metals. As a result, ce- vidual layers. It is also a way to increase the failure ramics have been subjected to a multitude of ballistic strength of ceramics by creating a layer with and dynamic behavior investigations [1-4]. However, sive stresses on the surface that will arrest the the widespread usage of ceramics is currently ham- cracks and achieve higher failure stresses [8]. The layer pered by their lack of the requisite toughness. The lat- composition, as well as the systems geometry, allows est developments in ceramic composites show that the the designer to control the magnitude of the residual use of layered materials is perhaps the most promising stresses in such a way that compressive stresses in the 0022-2461 o 2005 Springer Science+Business Media, Inc. DOI:10.1007/s10853-005-1923-x 5483JOURNAL OF MATERIALS SCIENCE 4 0 (2 005) 5483 – 5490 Robust design and manufacturing of ceramic laminates with controlled thermal residual stresses for enhanced toughness NINA ORLOVSKAYA Drexel University, 3141 Chestnut St., Philadelphia, PA 19104, USA E-mail: orlovsk@drexel.edu MYKOLA LUGOVY, VLADIMIR SUBBOTIN, OLEKSANDR RADCHENKO Institute for Problems of Materials Science, 3 Krzhizhanovskii St., 03142, Kiev, Ukraine JANE ADAMS Army Research Laboratory, Aberdeen Proving Ground, MD 21005, USA MUNJAL CHHEDA, JAMES SHIH Ceradyne Inc., 3169 Redhill Ave., Costa Mesa, CA 92626, USA JAG SANKAR, SERGEY YARMOLENKO North Carolina A&T State University, 1601 E. Market St., Greensboro, NC 27411, USA Boron carbide-silicon carbide ceramic composites are very promising armor materials because they are intrinsically very hard. However, their fracture toughness is not very high. Their ballistic performance could be significantly increased if the brittleness of these materials could be decreased. Here we report development of boron carbide-silicon carbide layered ceramics with controlled compressive and tensile stresses in separate layers. Such B4C-SiC laminates with strong interfaces can provide high apparent fracture toughness and damage tolerance along with high protection capabilities. The theory of heterogeneous layered systems was used to develop optimal design parameters allowing the evaluation and maximization of apparent fracture toughness. The layered composites were designed in a way to achieve high compressive residual stresses in thin B4C-SiC based layers and low tensile residuals stresses in thick B4C layers. The residual stresses were controlled by the phase composition of layers and the layers thickness. The estimated apparent fracture toughness was calculated for both three layered and nine layered composites. B4C-30 wt%SiC/B4C laminates were made based on the optimized design for high apparent fracture toughness. Processing of laminates involved preprocessing of powders, forming green tapes and hot pressing. Work is in progress to measure fracture toughness of laminates, as well as their strength, hardness and the ballistic performance.
C 2005 Springer Science + Business Media, Inc. 1. Introduction Ceramics offer a number of attractive properties. These include high specific stiffness, high specific strengths, low thermal conductivities, and chemical inertness in many environments. Ceramics and ceramic compos￾ites are attractive materials for use in armor systems due to low density, superior hardness, and compres￾sive strength values relative to metals. As a result, ce￾ramics have been subjected to a multitude of ballistic and dynamic behavior investigations [1–4]. However, the widespread usage of ceramics is currently ham￾pered by their lack of the requisite toughness. The lat￾est developments in ceramic composites show that the use of layered materials is perhaps the most promising method to control cracks and brittle fracture by deflec￾tion, microcracking, or internal stresses [5–7]. Lami￾nates with strong interfaces, combined with excellent fracture toughness and damage tolerance, can poten￾tially provide the highest ballistic performance. The way to achieve the highest possible fracture toughness is to control the level of residual stresses in the indi￾vidual layers. It is also a way to increase the failure strength of ceramics by creating a layer with compres￾sive stresses on the surface that will arrest the surface cracks and achieve higher failure stresses [8]. The layer composition, as well as the system’s geometry, allows the designer to control the magnitude of the residual stresses in such a way that compressive stresses in the 0022–2461
C 2005 Springer Science + Business Media, Inc. DOI: 10.1007/s10853-005-1923-x 5483