MATERIALS LETTE.S ELSEVIER Materials Letters 46(2000)65-69 www.elsevier.com/locate/matlet Mechanical properties and fracture behavior of Al,O3 laminates with different architectures Jihong She a ", Takahiro Inoue, Masato Suzuki, Satoshi Sodeoka, Kazuo Ueno Institute of Materials Research, German Aerospace Center(DLR, D-51147 Cologne, Germany Department of Energy Conersion, Osaka National Research Institute, Midorigaoka 1-8-31, Ikeda, Osaka 563-8577, Japan Received 18 April 2000, accepted 28 April 2000 Abstract Fibrous, multilayered and hybrid Al,O3 laminates were fabricated by extrusion and hot-pressing techniques. The effects of different architectures on the mechanical properties and fracture behavior are investigated. It is shown that hybrid laminates may provide a considerable flexibility and tailorability in mechanical behavior. An alternative arrangement of the fibrous and monolithic layers in hybrid laminates gives an average strength of up to 450 MPa, an apparent toughness of 11 MPa m/ and a fracture energy in excess of 2600 J/m2, with a non-catastrophic fracture behavior. 02000 Elsevier Science B v. All rights reserved PACS:81.05e;8105Mh8120.Hy,81.40.Np6220Mk Keywords: Mechanical properties; Fracture; Al,2O3; Laminates; Delamination 1. ntroduction Following Coblenz's method, Baskaran et al. ( 2-4 fabricated a variety of fibrous ceramics such as It has previously been shown that brittle ceramics Sic/C, SiC/BN and Si, N4/BN. Similarly, Clegg can be toughened by the introduction of crack-de- et al. [5, 6] developed multilayer SiC/C ceramics flecting interfaces. A well-known example is fiber Lately, multilayer Si, NA/BN [7, 8]ceramics were reinforced ceramic composites. However, expensive also successfully fabricated. Due to the deflection of ceramic fibers and some time-consuming processes cracks at the weak c or bn interfaces these fibrous such as chemical vapor deposition and or chemi- or layered ceramics exhibited a fracture behavior cal vapor deposition are required for the fabrication similar to that of fiber-reinforced cer of such composites. To overcome this limitation, Ites Coblenz [1] demonstrated a new concept of"fibrous ceramics" which can be manufactured from com- The objective of the present work is to show that a non-catastrophic fracture behavior can be attained mercially available ceramic powders via conven- for fibrous, multilayered and hybrid Al2O3 lami- tional ceramic- and polymer-processing technology nates, which were fabricated by stacking the mon lithic and/ or fibrous Al,, layers in different fash- Corresponding author. Tel: +49-2203-6012560; fax: +45 ion The effects of different architectures on the 2203-696480 mechanical properties and fracture behavior were E-mail address: jhshe hotmail com(. She) investigated 00167-577X/00/S-see front matter o 2000 Elsevier Science B V. All rights reserved 144-0November 2000 Materials Letters 46 2000 65–69 Ž . www.elsevier.comrlocatermatlet Mechanical properties and fracture behavior of Al O laminates 2 3 with different architectures Jihong She a,), Takahiro Inoue b , Masato Suzuki b , Satoshi Sodeoka b , Kazuo Ueno b a Institute of Materials Research, German Aerospace Center DLR , D-51147 Cologne, Germany ( ) b Department of Energy ConÕersion, Osaka National Research Institute, Midorigaoka 1-8-31, Ikeda, Osaka 563-8577, Japan Received 18 April 2000; accepted 28 April 2000 Abstract Fibrous, multilayered and hybrid Al O laminates were fabricated by extrusion and hot-pressing techniques. The effects 2 3 of different architectures on the mechanical properties and fracture behavior are investigated. It is shown that hybrid laminates may provide a considerable flexibility and tailorability in mechanical behavior. An alternative arrangement of the fibrous and monolithic layers in hybrid laminates gives an average strength of up to 450 MPa, an apparent toughness of ;11 MPa m1r2 and a fracture energy in excess of 2600 Jrm2 , with a non-catastrophic fracture behavior. q 2000 Elsevier Science B.V. All rights reserved. PACS: 81.05.Je; 81.05.Mh; 81.20.Hy; 81.40.Np; 62.20.Mk Keywords: Mechanical properties; Fracture; Al O ; Laminates; Delamination 2 3 1. Introduction It has previously been shown that brittle ceramics can be toughened by the introduction of crack-de￾flecting interfaces. A well-known example is fiber￾reinforced ceramic composites. However, expensive ceramic fibers and some time-consuming processes such as chemical vapor deposition andror chemi￾cal vapor deposition are required for the fabrication of such composites. To overcome this limitation, Coblenz 1 demonstrated a new concept of w x Afibrous ceramicsB, which can be manufactured from com￾mercially available ceramic powders via conven￾tional ceramic- and polymer-processing technology. ) Corresponding author. Tel: q49-2203-6012560; fax: q49- 2203-696480. E-mail address: jhshe@hotmail.com J. She . Ž . Following Coblenz’s method, Baskaran et al. 2–4 w x fabricated a variety of fibrous ceramics such as SiCrC, SiCrBN and Si N3 4rBN. Similarly, Clegg et al. 5,6 developed multilayer SiC w x rC ceramics. Lately, multilayer Si N rBN 7,8 ceramics were w x 3 4 also successfully fabricated. Due to the deflection of cracks at the weak C or BN interfaces, these fibrous or layered ceramics exhibited a fracture behavior similar to that of fiber-reinforced ceramic compos￾ites. The objective of the present work is to show that a non-catastrophic fracture behavior can be attained for fibrous, multilayered and hybrid Al O lami- 2 3 nates, which were fabricated by stacking the mono￾lithic andror fibrous Al O layers in different fash- 2 3 ion. The effects of different architectures on the mechanical properties and fracture behavior were investigated. 00167-577Xr00r$ - see front matter q 2000 Elsevier Science B.V. All rights reserved. PII: S0167- 577X 00 00144-0 Ž