Qualification Testing of Electroformed Nanostructured Cobalt-Alloy Bushings

Dr. Alan Grieve | Naval Air Warfare Center, Aircraft Division

WP-201624

Objective

The objective of this project is to demonstrate the cost-effective manufacturing and performance of electroformed nanostructured cobalt-alloy bushings for use in Department of Defense (DoD) weapon platforms to eliminate the need for toxic copper-beryllium (CuBe) bushings. The project seeks to mature the technology to the stage where they are fully demonstrated, validated, and qualified on select repair and overhaul components and ready for depot implementation.

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Technology Description

Nanostructured cobalt-alloy materials have been fabricated using a unique pulsed electroforming process. The pulse plating process favors nucleation of new grains over growth of existing grains, resulting in an ultra-fine grain structure throughout the entire thickness of the material deposit. Nanostructured materials have grain sizes in the order of 10-100nm, compared to around 1μm for conventional materials. The Hall-Petch equation describes the increase in strength of metals with decreasing grain size. In effect, the grain boundaries act as pinning points, impeding further dislocation propagation. The resulting nanostructured materials are of higher hardness and have higher yield strength than most conventional materials. They have great potential as a novel bushing material that could replace both CuBe and conventional stainless steel bushings in aluminum aircraft structures.

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Benefits

The successful execution of this project will lead to a significant reduction in the use of toxic beryllium-containing bushing alloys in low-frequency rotational wear defense applications. In addition to improvement of the health and safety concerns of DoD workers, the performance advantages of the nano cobalt-alloy bushing over that of CuBe and other alternatives are expected to lead to enhanced product lifetime and reduced operating costs. Specific benefits include:

  • Superior mechanical and tribological properties to CuBe, steel, and alternative bushing materials, resulting in longer life and ability to handle higher loads.
  • Better galvanic match with aluminum structures, less corrosion compared to CuBe and steel bushings in contact with aluminum structures.
  • Near net shape manufacturing method resulting in very little material waste during manufacturing (high buy-to-fly ratio).
  • Ability to produce bushings on-demand to alleviate delays due to material supply issues in critical repair and overhaul situations.

The nanostructured cobalt alloys potentially offer wide cross-platform applicability as a replacement material for all low-frequency rotational wear applications within the DoD. (Anticipated Project Completion - 2019)

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Points of Contact

Principal Investigator

Dr. Alan Grieve

Naval Air Warfare Center Aircraft Division

Phone: 301-342-6807

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