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  • 1.  HVAF Process?

    Posted 07-24-2023 15:24

    I'm wondering about the community's views on HVAF for spraying wear coatings. It seems the lower heat could solve some problems around oxidization of feedstock and overheating. Wondering what the community's take is on this technology, and why/where it's better or worse than HVOF?



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    GREGORY HUSTON
    Machinist Lead Hand
    WEST FRASER ELECTROMECHANICAL
    Prince George BC
    2509608339
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  • 2.  RE: HVAF Process?

    Posted 07-25-2023 07:47

    Hello Gregory, I'Ve worked with HVAF on and off since the first UniqueCoat system was installed at Uni West (Sweden) more than 10 years back. Its proven to be extremely capable in producing wear coatings in that time, particularly tungsten carbide based coatings. It does also very well in producing coatings based on chrome carbide and a number of metallic coatings too. We made some exceptionally good bond coats for thermal barrier coatings with it; performance on par with Vacuum plasma spray. 

    Generally the accepted improvement comes from the lower flame temperature and higher velocities, so reducing the chance of oxidation or decarburization in flight. There is sometimes a sacrifice in terms of deposition efficiency, though this can be countered somewhat by correct selection of powder feedstock type and size cut. Unlike HVOF, it does need a pretty powerful air compressor to manage the required air consumption. The total cost in the end requires looking at the whole process. 

    Since that first machine was installed at the university , my colleagues have been involved in selling a number of systems to companies that had formerly used HVOF or were considering HVOF originally, before changing to HVAF. I know of a number of other industrial driven development projects where the HVAF process has outperformed the best that the HVOF equipment producers can throw at it. 

    That I would say is my small snapshot of things from my contact with the technology. I guess others will tell you more. 

    Regards, Nick



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    Nicholas Curry
    Consultant
    Thermal Spray Innovations
    Bruck an der Großglocknerstraße
    +436705059479
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  • 3.  RE: HVAF Process?

    Posted 08-01-2023 08:04

    Hi Gregory,

    I am Application Development Engineer at Höganäs and I am mainly working with thermal spraying projects.

    I agree with Nicholas and I can definitely say that the HVAF process and materials evolved in the last few year a lot. HVAF, especially so called Net Shape Coatings, play meanwhile an important role, e.g. in the field of Hard Chrome Replacement.

    There are several benefits from HVAF coatings. I run out of words here in the comment section, but I will name a few:

    • Feed rates often higher than traditional HVOF
    • very thin and DENSE coatings possible (with right material and parameter settings)
    • often no need for surface activation or grit blasting
    • Ra (as-sprayed) < 1.6µm (with right material and parameter settings) => less post machining (grinding, polishing)
    • ...

    At Höganäs we have a wide material portfolio for HVAF applications and all HVAF systems. We even have a Customer Service Center near Houston TX equipped with the latest HVAF systems to support all sorts of developments (as well and FS, HVOF, APS, PTA and Laser Cladding). Other Service Centers are in Sweden, Germany, India and Shanghai. 

    If you wish a HVAF and materials deep dive or if you have a specific issue, feel free to contact us via email (amperit.technicalsupport@hoganas.com)

    Best Regards,

    Manuel

     



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    Manuel Schubert
    Höganäs Germany GmbH
    Goslar
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