# Reactive Laser Synthesis of Ultra-high-temperature Ceramics HfC, ZrC, TiC, HfN, ZrN, and TiN for Additive Manufacturing

**Authors:** Adam B. Peters, Chuhong Wang, Dajie Zhang, Alberto Hernandez, Dennis C. Nagle, Tim Mueller, James B. Spicer  
**arXiv:** [2208.02041](https://arxiv.org/abs/2208.02041)  
**Date:** 2022-08-03  
**Summary page:** https://www.summarizepaper.com/en/paper/2208.02041v1/

## Key points

- Ultra-high-temperature ceramics (UHTCs) are known for their resilience to extreme temperatures, chemically aggressive environments, wear, and mechanical stress.
- Utilization of UHTCs in laser-based additive manufacturing processes has faced challenges.
- Selective laser reaction sintering (SLRS) techniques were explored to produce near net-shape UHTC ceramics including HfC, ZrC, TiC, HfN,ZrN,and TiN.
- Group IV transition metal and metal oxide precursor materials were used for SLRS processing in CH4 or NH3 gas.
- Processing single-component precursors led to impressive yields of near stoichiometric UHTC phases but induced residual stresses and cracking due to volumetric changes.
- Composite metal/metal oxide precursors were introduced to effectively manage volume changes during conversion process.
- SLRS techniques show potential for producing high-quality UHTC ceramics through additive manufacturing processes.

## Summary

Ultra-high-temperature ceramics (UHTCs) are highly sought-after structural materials known for their exceptional resilience to extreme temperatures, resistance to chemically aggressive environments, wear, and mechanical stress. Despite their numerous advantageous properties, the utilization of UHTCs in laser-based additive manufacturing (AM) processes has faced significant challenges. In a recent study conducted by Adam B. Peters, Chuhong Wang, Dajie Zhang, Alberto Hernandez, Dennis C. Nagle, Tim Mueller, and James B. Spicer, selective laser reaction sintering (SLRS) techniques were explored as a means to produce near net-shape UHTC ceramics including HfC, ZrC, TiC, HfN,ZrN,and TiN. The research focused on utilizing Group IV transition metal and metal oxide precursor materials that were chemically converted and reaction-bonded into layers of UHTCs through single-step selective laser processing in CH4 or NH3 gas. This approach was designed to be compatible with prevailing powder bed fusion techniques commonly used in additive manufacturing processes. Initially investigating the conversion of both metals (Hf,Zr and Ti) and metal oxides (HfO2,ZrO2,and TiO2) particles allowed the researchers to examine the reaction mechanisms and volume changes associated with SLRS of single-component precursor systems. The results showed that SLRS processing of either metal or metal oxide alone led to the production of near stoichiometric UHTC phases with impressive yields reaching up to 100 wt% total for carbides and nitrides. However,it was noted that when using single component precursors,gas-solid reactivity induced volumetric changes that resulted in residual stresses and cracking within the product layer. To address these challenges effectively mitigate conversion-induced stresses, composite metal/metal oxide precursors were introduced. These composite precursors helped compensate for the volume changes experienced during conversion; expanding during the conversion process for metals or contracting for metal oxide precursors. This comprehensive study sheds light on the potential of SLRS techniques for producing high-quality UHTC ceramics through additive manufacturing processes. By understanding the intricacies of precursor material reactions and employing innovative solutions such as composite precursors to manage volume changes effectively, researchers are paving the way for advancements in utilizing UHTCs in extreme temperature applications with enhanced reliability and performance characteristics.