text: The best HVOF system for MCrAlY
  03-27-2015, 01:55 PM,
  Our company wants to buy HVOF system for turbine blades and vanes coating (MCrAlY).
  Base material – Inconel 738.
  Thickness - up to 400 microns.
  Please, give me advice which type of system is the best for this task.
  03-27-2015, 02:56 PM,
  RE: The best HVOF system for MCrAlY
  (03-27-2015, 01:55 PM)DMack Wrote: Hi Everybody!
  Hi DMack,
  Spraying of thick MCrAlY coatings best quality is obtained by spraying with high-velocity plasma jet (for example, 100HE™ Plasma Spray System) in vacuum on a hot substrate. Before spraying the turbine blade is heated in vacuum to temperatures of about 900 ° C. Adhesion strength of coating MCrAlY at alloy Inconel after vacuum plasma deposition (VPS) on the hot substrate can be > 300 MPa. Adhesion of the same coating, spraying with method HVOF, is < 80 MPa, and for thick coatings (> 200 microns) even less.
  03-27-2015, 05:53 PM,
  HVAF can apply very high quality MCrAlY coatings > 400 um thick and achieve very high bond strength. The cost will be much lower than vacuum plasma spray. You could do it in your existing spray booth. Contact me offline, and we can discuss the hardware needed and if you can use some of your existing equipment.
  03-27-2015, 07:12 PM, (This post was last modified: 03-27-2015, 09:15 PM by Vadim Verlotski.)
  (03-27-2015, 05:53 PM)djewell Wrote: HVAF can apply very high quality MCrAlY coatings > 400 um thick and achieve very high bond strength. The cost will be much lower than vacuum plasma spray. You could do it in your existing spray booth. Contact me offline, and we can discuss the hardware needed and if you can use some of your existing equipment.
  I myself am against the use of VPS, if you can do without, but this method is the standard for MCrAlY-coatings on turbine blades . In the case of vacuum and high temperature of substrate can obtain almost perfect metallurgical bond between the coating and the substrate, which is formed by diffusion. HVAF provides a dense coating with low residual stresses, but the diffusion to the substrate can it not give.
  Of course, HVAF or HVOF MCrAlY-coating can be subjected to the heat treated after deposition at 900-1000°C, but oxide contents in the such coating will be greater than in the VPS coating.
  03-30-2015, 02:03 PM, (This post was last modified: 03-30-2015, 02:09 PM by DMack.)
  Our company has EB PVD ceramic and metallic coating equipment for aircraft components. Additionally we use MaxJet II HVOF unit for carbite (WC12%) coating. At the moment we are looking for a cheaper way for IGT components metallic coating. As I know, main heavy-duty turbine manufacturers (GE, Alstom, Siemens, MHI) use HVOF metallic coating (bond coat) with APS ceramic coating for turbine blades and vanes. Thus, after consultation with experts in this area, we decided to look for HVOF equipment.
  Hi dgewel,
  It is interesting to use HVAF instead of HVOF, but could you give a link to the practical use of this type of coverage. Perhaps there is a company website or publication.
  03-30-2015, 07:34 PM,
  I can send you a test report done by University West in Sweden. They evaluated some metallic coatings for the properties you described. In short, they found incredible high bond strength (up to 189 MPa) and very high density. They had to braze the bond test coupons into their machine in order to measure them.
  04-01-2015, 09:11 AM,
  Heat-resistant coating type MeCrAlY (Me-Ni,Co depend of working temp.) should be applied or vacuum methods PVD (arc or magnetron) or gas-thermal but in a dynamic vacuum.
  Coating on the air leads to a higher content of oxides in this coatings. This in turn leads to difficulties of diffusion of such elements as Al and Cr to the surface of the coating and formation of a protective oxide film.So works this coating.
  04-03-2015, 09:09 AM,
  Hi Dr. Boris,
  I know that PVD coating is the best for aircraft components. But now a lot of companis use HVOF MCrAlY for IGT components. And further, the more IGT manufacturers are using this technology. Therefore we are looking for HVOF equipment for the process.
  04-07-2015, 10:41 PM,
  Talk to the application experts at Metco. Years ago they developed HVOF spraying parameters for MCrAlY coatings using the Diamond Jet system.
  04-15-2015, 08:40 PM,
  Vadim Verlotski,
  HVAF can also provide a diffusion bond to the substrate. HVAF coatings have practically 0 oxidation, so there is nothing between the coating and the substrate to impede the bond. It has been shown in XRD analyses that HVAF coatings diffuse into the substrate. Recently, bond strengths of HVAF coatings over 200 MPa have been measured in a special test fixture at University West in Sweden.
  04-16-2015, 01:34 PM, (This post was last modified: 04-16-2015, 01:41 PM by Vadim Verlotski.)
  (04-15-2015, 08:40 PM)djewell Wrote: Vadim Verlotski,
  In order to obtain metallurgical bond between two metal surfaces must fulfill two conditions:
  1. All metallic surfaces should be free from oxide films. Even oxide film with a thickness of a few nanometers prevent the formation of a metallurgical bond (oxide films must be removed).
  2. The temperature of both surfaces should be high enough to start diffusion between the two metals.
  When spraying MCrAlY coatings to the Inconel-substrate by the method of HVAF both of these conditions are not met:
  - The oxide film on the surface of the substrate and the particles are not removed, but become thicker.
  - Temperature of the particles and the substrate substantially below that necessary for diffusion (> 800 ° C).
  For some metallurgical bond is necessary to used the heat treatment of details with HVAF-coat at temperatures > 800 ° C. I suppose that during the preparation of samples for the measurement of bond strength in Sweden, such heating has been made (high temperature brazing). Without heat treatment a bond strength of HVAF-coat to the substrate can not be higher than 100 MPa.
  01-16-2017, 08:19 PM, (This post was last modified: 01-16-2017, 08:35 PM by Lou Jaworski.)
  There are advantages to the many systems out their anybody or company that tells you this is the best HVOF system is either lying or doesn't know what the hell they are talking about. I had almost every system in existence at the time and conducted R&D for the DOD and internal applications comparing coating properties, application variables all different materials ( even ceramics with HVOF) operating varibles etc... Besides running repair, Technical Adviser for outages, manufacturing and coating companies for the last 27 years.
  I have wide range of application experience making, repairing, coating and operating IGT components and turbines. If you want to do it correctly give me a call i work with all the OEMs of Spray equipment, IGT repair facilities, IGT OEM manufactures 832-646-8709
  01-21-2017, 04:54 AM, (This post was last modified: 01-21-2017, 05:19 AM by david.wang.)
  david.wang
  You may try Kermetico Convertible Thermal Spraying Equipment Working in HVOF Mode. You will get higher D.E. and better coating quality. Operational cost of coating will be much lower as compared to conventional JP or DJ HVOF systems.
  MCrAlY bend test liaemars 1 1,240 08-26-2018, 01:44 PM
  HVOF System Considerations Josgates 5 1,539 07-10-2018, 03:01 PM
  heat treatment of MCrAlY coatings clover 4 6,250 06-26-2017, 12:55 PM
  MCrAlY on steel for general repair MVagusta 2 2,418 08-05-2016, 10:06 AM
  Is it possible to spray powder established for gas based HVOF in Fluid HVOF system?? sreenuvundela 0 2,396 04-18-2016, 07:52 AM