Accession Number:

ADA411113

Title:

Synthesis and Behavior of Nanostructured Coatings Using Thermal Spraying

Descriptive Note:

Final rept. 01 Oct 1999 - 31 Oct 2002

Corporate Author:

CALIFORNIA UNIV DAVIS

Personal Author(s):

Report Date:

2003-01-22

Pagination or Media Count:

9.0

Abstract:

Potential applications of thermal spraying coatings span the entire spectrum of technology, from thermal barrier coatings for turbine blades to wear resistant rotating parts. The goal of this research program was to synthesize and characterize nanostructured thermal spraying coatings. The specific objectives were as follows 1 to synthesize nanostructured powders for fabrication of nanostructured thermal spraying coatings 2 to improve the spray technology for spraying nanostructured powders and 3 to characterize the nanostructured materials powder as well as coatings for structure, composition, properties, and performance. One of the programs accomplishments was the successful synthesis of diverse nanostructured feedstock powders using mechanical milling in different media. Chemical composition and structural analyses were performed for the powders milled for a pre-determined interval so that the milling process and behavior of resultant powder was monitored and optimized. Another accomplishment was the 20 increase in hardness and 28 increase in wear resistance in nanostructured Cr3C2-NiCr coatings. Nanostructured powders and conventional powders were thermally sprayed and their behavior compared using a High Velocity Oxygen Fuels HVOF facility equipped with an inflight powder diagnostics system. A third accomplishment was the characterization of the nanostructured coatings in terms of hardness, wear-resistance, and microstructures using Nanoidentor, SEM, X-ray diffraction, and TEM. On the basis of the feedback from analysis of the physical properties of the coatings, the spraying parameters were modified and optimum spraying conditions were reached for an individual nanostructured powder. That is, techniques for synthesizing nanostructured WC-18Co coatings containing a low amount of non-WC carbide phases were developed as were thermal treatment techniques to further improve the physical performance of such coatings. 1 table, 8 figures, 64 refs.7

Subject Categories:

  • Coatings, Colorants and Finishes
  • Properties of Metals and Alloys

Distribution Statement:

APPROVED FOR PUBLIC RELEASE