Effect of the Machining Method on the Catalycity and Emissivity of ZrB2 and ZrB2–HfB2‐Based Ceramics

The emissivity and the catalytic efficiency related to atomic oxygen recombination were investigated experimentally in the range 1000-2000 K for ZrB 2 and ZrB 2 -HfB 2 -based ceramics. In order to evaluate the effect of the machining method, two series of samples, one prepared by electrical discharge machining and the other machined by diamond-loaded tools, were tested. High emissivity (about 0.7 at 1700 K) and low recombination coefficients (on average 0.08 at 1800 K) were found for all the materials. The experimental data showed an effect of the surface machining on the catalytic behavior only on the ZrB 2 -based composite; conversely, small variations were found in the recombination coefficients of ZrB 2 -HfB 2 -based samples for the different machining processes. The surface finish affected the emissivity at lower temperatures in both compositions, with the effect becoming negligible at temperatures above 1500 K.

[1]  Mark M. Opeka,et al.  Mechanical, Thermal, and Oxidation Properties of Refractory Hafnium and zirconium Compounds , 1999 .

[2]  F. Monteverde.  Beneficial effects of an ultra-fine α-SiC incorporation on the sinterability and mechanical properties of ZrB2 , 2006 .

[3]  E. Jumper,et al.  Model for Oxygen Recombination on Reaction-Cured Glass , 1994 .

[4]  J. Robert,et al.  Physico-chemical behavior of carbon materials under high temperature and ion irradiation , 2001 .

[5]  W. Fahrenholtz.  The ZrB2 Volatility Diagram , 2005 .

[6]  William J. Marinelli,et al.  Spacecraft thermal energy accommodation from atomic recombination , 1991 .

[7]  J. Robert,et al.  Concentrated Solar Energy as a Diagnostic Tool to Study Materials Under Extreme Conditions , 2002 .

[8]  J. Yang,et al.  Thermal stability of refractory carbide/boride composites , 2002 .

[9]  Donald T. Ellerby,et al.  High‐Strength Zirconium Diboride‐Based Ceramics , 2004 .

[10]  Ronald J. Willey,et al.  Comparison of kinetic models for atom recombination on high-temperature reusable surface insulation , 1993 .

[11]  J. Zaykoski,et al.  Oxidation-based materials selection for 2000°C + hypersonic aerosurfaces: Theoretical considerations and historical experience , 2004 .

[12]  Alida Bellosi,et al.  Processing and properties of zirconium diboride-based composites , 2002 .

[13]  Raffaele Borrelli,et al.  Catalytic and Radiative Behaviors of ZrB2-SiC Ultrahigh Temperature Ceramic Composites , 2006 .

[14]  A. Bellosi,et al.  The resistance to oxidation of an HfB2–SiC composite , 2005 .

[15]  Donald T. Ellerby,et al.  Processing, properties and arc jet oxidation of hafnium diboride/silicon carbide ultra high temperature ceramics , 2004 .

[16]  A. Bellosi,et al.  Efficacy of HfN as sintering aid in the manufacture of ultrahigh-temperature metal diborides-matrix ceramics , 2004 .

[17]  Guy Cernogora,et al.  Atomic oxygen recombination on fused silica: modelling and comparison to low-temperature experiments (300 K)* , 2000 .

[18]  Bridget R. Rogers,et al.  Catalytic Atom Recombination on ZrB2/SiC and HfB2/SiC Ultrahigh-Temperature Ceramic Composites , 2004 .

[19]  William G. Fahrenholtz,et al.  Thermodynamic Analysis of ZrB2–SiC Oxidation: Formation of a SiC‐Depleted Region , 2007 .

[20]  F. Monteverde,et al.  Resistance to Thermal Shock and to Oxidation of Metal Diborides–SiC Ceramics for Aerospace Application , 2007 .

[21]  Alida Bellosi,et al.  Oxidation of ZrB2-Based Ceramics in Dry Air , 2003 .

[22]  A. Bellosi,et al.  Development and characterization of metal-diboride-based composites toughened with ultra-fine SiC particulates , 2005 .

[23]  D. Hernandez,et al.  A concept to determine the true temperature of opaque materials using a tricolor pyroreflectometer , 2005 .

[24]  Eric J. Jumper,et al.  Model for oxygen recombination on silicon-dioxide surfaces , 1991 .

[25]  Yukio Hirai,et al.  Surface damage in ZrB2-based composite ceramics induced by electro-discharge machining , 1991 .

[26]  Jonathan A. Salem,et al.  Evaluation of ultra-high temperature ceramics foraeropropulsion use , 2002 .

[27]  M. Balat,et al.  Ceramics Catalysis Evaluation at High Temperature Using Thermal and Chemical Approaches , 1999 .

[28]  H. C. Graham,et al.  The High‐Temperature Oxidation Behavior of a HfB2 + 20 v / o SiC Composite , 1975 .

[29]  A. Bellosi,et al.  Advances in microstructure and mechanical properties of zirconium diboride based ceramics , 2003 .

[30]  William G. Fahrenholtz,et al.  Refractory Diborides of Zirconium and Hafnium , 2007 .

[31]  William G. Fahrenholtz,et al.  Processing and characterization of ZrB2-based ultra-high temperature monolithic and fibrous monolithic ceramics , 2004 .

[32]  R. Berjoan,et al.  Recombination coefficient of atomic oxygen on ceramic materials under earth re-entry conditions by optical emission spectroscopy , 2003 .

[33]  A. Bellosi,et al.  Processing and properties of ultra-high temperature ceramics for space applications , 2008 .

[34]  M. Balat-Pichelin,et al.  Structural modifications of carbon–carbon composites under high temperature and ion irradiation , 2005 .

[35]  L. Bedra,et al.  Recombination of atomic oxygen on α-Al2O3 at high temperature under air microwave-induced plasma , 2007 .