Spatio-temporally resolved thermal transport processes of ultra-high temperature ceramics
Abstract
,Abstract Approved for Public ReleaseTitle: Spatio-temporally resolved thermal transport processes of ultra-high temperature ceramics,PI: Patrick E. HopkinsThe overall goal of this proposed project is to study the fundamental thermodynamics and thermal properties of, novel ultra-high temperature materials when subjected to extreme heat fluxes and large temperature excursions in reacting environme,ks typical during hypersonic flight dictates the reliability and performance of hypersonic vehicles. The leading edge of hypersoni,c vehicles is a region of intense thermal fluxes, the power densities of which can initiate failure of the leading edge. During hype,rsonic flight, the intense, localized and rapid heating of leading edges can routinely lead to several failure mechanisms of ultrahi,gh temperature materials, including: i) local nonequilibrium temperatures much higher than the melting point; ii) extreme thermal gr,adients leading to thermomechanical damage; and iii) high rates of oxidation from the extreme thermal and chemical gradients. The e,xtreme spatial gradients in temperature lead to spatially varying mechanical and thermal properties. Thus, a critical need exists t,o measure spatial and temporal changes in thermal conductivity and spectral emissivity of UHTCs when subjected to relevant hypersoni,c environments. The objective of this proposed program is to experimentally measure the thermal properties (thermal conductivity, h,eat capacity and spectral emissivity) of current and next generation UHTCs with a novel experimental method that can spatially and t,emporally resolve the changes in thermal properties at time and length scales that dictate material failure when subjected to extrem,e power fluxes typical in hypersonic environments. In particular, the experimental metrologies developed in this work will be appli,ed to ultrahigh temperature borides and carbides, including high entropy borides and carbide. An additional major advance in this p,roposed work is the extension of thermoreflectance spectroscopies in Hopkins lab to measure the spectral emissivity of materials, t,hus providing the superior spatial and temporal resolution afforded by thermoreflectance technique in the measurement of emissivity;, this will result in the development of a new metrology to provide local measurements of spectral and temporal emissivity changes of, UHTCs during high heat flux laser heating.The proposed effort to measure thermal transport and spectral emissivity in UHTCs is dire,ctly relevant to Navy needs for reliably and performance of hypersonic transport, weapons and defense. These UHTCs must ensure high, temperature and high power flux protection and functionality to survive the intense environments of high Mach number flight. Our p,roposed work will create the capability to measure material thermal responses under hypersonic heat loads at the lab level with focu,sed laser sources and probes that will allow for orders of magnitude higher throughput in material testing and evaluation compared t,o existing facilities, which will provide sufficient information for validation prior to full flight simulations of relevance to the, Navy and DoD in general. Related to this high throughput tasting an additional major contribution to future naval relevance in this, work: the development of novel metrologies to measure temperature, emissivity, thermal conductivity, and heat capacity of high temp,erature materials. We expect technology transfer of these thermometry metrologies to military and defense labs for material evaluat,ion, such as the Naval Research Laboratory.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 08, 2022
- Source ID
- N000142212139
Entities
People
- Patrick Hopkins
Organizations
- Office of Naval Research
- United States Navy
- University of Virginia