Cold Spray of Functionally Graded Aluminum Metal Matrix Composite Coatings Reinforced with Boron Carbide and Boron Nitride Nanotubes
Abstract
Aluminum 7075 alloys are extensively utilized in the aerospace industry for their relatively high specific strength coupled with decent corrosion resistance and cost-effectiveness. Being an Al alloy, however, the material suffers from low wear resistance. Cold gas dynamic spray, commonly known as cold spray, is a thermal spray technique applicable for on-site repair of metallic surfaces, particularly Al, as well as coating onto Al substrates to enhance wear resistance among other properties. Improving the wear resistance of Al requires the integration of a reinforcing filler/s. Notably, there is a research gap regarding the cold spray application of compositionally graded, dual-reinforced aluminum metal matrix composites (Al-MMC). In this study, aircraft-grade aluminum (Al7075) underwent the cold spray process with reinforcement from boron carbide (B4C) and boron nitride nanotubes (BNNT). The creation of a functionally graded coating (FGC) was achieved through high-energy ball milling, incorporating varying compositions of 10, 15, and 20 vol. percent muB4C. This coating included a top layer with 2 vol.% BNNT and 2 vol.% nB4C. Comparative assessments of the different coating layers were conducted, with a specific focus on evaluating their subsequent wear resistance. Remarkably, all muB4C compositions exhibited sustained or enhanced wear resistance, despite experiencing low deposition rates, especially in the layers containing 2 vol. percent BNNT and 2 vol. percent nB4C.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 2023
- Accession Number
- AD1225528
Entities
People
- Richard L. Schmidt
Organizations
- Naval Postgraduate School