Non-Carbon-Based Thermal Protection Systems for Hypersonic Movers

Overview

Hypersonic vehicles are exposed to harsh operating conditions, which require the development and implementation of a thermal protection system (TPS). Many existing carbon-based systems experience a degree of ablation and emit carbide compounds that reduce the effectiveness of the TPS and increase the detectability of the vehicle. Due to these downsides of a carbon-based TPS, our team was tasked with continuing the analysis of determined non-carbon-based candidate material Zirconium diboride and evaluating its potential for hypersonic applications through a series of mechanical tests.

Objectives

Optimize Spark Plasma Sintering (SPS) parameters to achieve high Zirconium diboride density

Select appropriate mechanical tests to evaluate material readiness for hypersonic applications

Perform and develop mechanical testing

Demonstrate Zirconium diboride capabilities in a gas gun test to simulate hypersonic conditions

Comparison of Zirconium diboride results to existing carbide thermal protection systems

Approach

Researched and identified optimal Spark Plasma Sintering Parameters for candidate material Zirconium diboride

Sintered Zirconium diboride powder to produce a puck test specimen. A total of five pucks were produced

Determined the test puck specimen density through an Archimedes density evaluation to ensure sintering parameters were properly optimized. Our team was aiming for theoretical density above 95%

Selected a series of mechanical tests to evaluate material performance (Vicker’s Hardness, Emissivity, Compressive Strength (Four-point bend), Thermo-gravimetric Analysis (TGA)

Evaluate results of mechanical tests to existing Zirconium diboride data and other competing Carbon-based TPS

Performed a final gas gun test to simulate actual hypersonic conditions against test puck specimens

Outcomes

Optimized Spark Plasma Sintering parameters produced five new Zirconium diboride pucks, with each puck achieving a density above 95%

Thermo-Gravimetric Analysis (TGA) in an oxygen environment revealed an average weight gain of about 2%, showing oxidative behavior at about 790C

Four-point compressive strength results revealed an average strength of 274.6 MPa, which is higher than typical Carbon-Carbon materials which show values between 100-150 MPa. Vicker’s Hardness testing revealed an average HV of 1152.63, which was within expectations

Emissivity testing had values within the .85 value range. Our group was expecting values between .8 and .9, and these values are expected for a material of this nature