HVOF Coating Case Study for Power Plant Process Control Ball Valve Application (original) (raw)
Related papers
2020
In petroleum production and separation processes frequently the components suffer wear and corrosion due to the contact with the corrosive fluid which could be contain solid particles. In certain dynamics equipment like as ball valves, the deterioration generated causes the operations equipment exit at short times about a month. The main elements of the valves deteriorated are the seats and corks, which are made of 4140 steel. The aim of the present research was evaluating extend the life time of the components using two thermal spray coatings systems: WC-12%Co alloy by HVOF and FeCrB alloy by AWS. The evaluation of wear resistance of these coatings was achieved by means of abrasion wear tests according to ASTM G65-C. The microhardness of the coating was determined by means of Vickers indentation using a load of 300g and the corrosion behavior was evaluated by potentiodynamic polarization tests. The results showed that the best performance in corrosion and abrasion conditions corres...
Microstructural examination of HVOF chromium carbide coatings for high-temperature applications
Journal of Thermal Spray Technology, 1996
Chromium carbide/nickel chromium coatings obtained by the high-velocity oxyfuel thermal spray process were characterized using conventional and high-resolution microscopy to identify the complex microstructure that results from this thermal spraying technique. Thermal cycling and long isothermal treatment were studied, as were the adhesion properties of as-coated and thermally treated samples.
Wear, 2001
The appropriate selection of bulk materials and coatings of valve components is an important factor for the economic success of oil and gas production activities in the petrochemical field. Materials and coatings are important because particle erosion and surface wear are associated to corrosion by hydrogen sulphide during oil and gas flow. The wear of high pressure valves of gas system will lead to pollution, safety problems and cost increases. The most common solution of these problems is the deposition of hard materials as tungsten carbide or chromium carbide by thermal spray. These coatings are deposited by high velocity oxygen fuel (HVOF) thermal spray process to obtain a very high hardness with excellent cohesion and adhesion. Tungsten carbide cobalt-chromium based coating, chromium carbide nickel-chromium coating as well as Inconel 625 have been adopted in the specifications of petrochemical companies and their behaviour and wear, erosion and corrosion properties are reported in the literature.
2015
Tube Furnace CVD Apparatus 22. Sample Surface Temperature Measurement 23. XRD results for chromium films subjected to CVD process in the temperature range of 900°C-1000°C 24. Inconel Retort CVD Apparatus 25. XRD results for chromium films subjected to the CVD process outlined above at 1000°C and 1050°C 26. XRD patterns of the Cr 2 O 3 feedstock powder used in this work (top scan) and the resulting plasma-sprayed coating (bottom scan), indicating no appreciable compositional changes as a result of the deposition process. 27. Cross-sectional SEM micrograph of plasma-sprayed Cr 2 O 3 (top coat), showing a complex pore structure containing globular voids, interlamellar porosity and intralamellar microcracks. 28. XRD patterns of plasma-sprayed Cr 2 O 3 after various reduction times (0.1-0.3 h) at 1000ºC, showing coating phase evolution from Cr 2 O 3 to binder-free Cr 3 C 2. 29. Cross-sectional SEM micrographs of plasma-sprayed Cr 2 O 3 after various reduction times at 1000 ºC, illustrating characteristics of the mechanism of reduction to binder-free Cr 3 C 2 : (a) 0.1 h, (b) 0.2 h, (c) 0.3 h. 30. Void formation in the Cr 3 C 2 phase formed from the reduction of plasma-sprayed Cr 2 O 3. Label "A" corresponds to unconverted Cr 2 O 3 and label "B" corresponds to newly-formed microporous Cr 3 C 2. 31. XRD coating phase evolution of an electrodeposited Cr coating after 6 and 12 h of posttreatment with methane-containing gas at 1000 °C. 32. SEM micrograph of coating porosity in an (a) electrodeposited Cr coating, (b) electrodeposited Cr coating after 6 h of post-treatment with methane-containing gas at 1000 °C and (c) electrodeposited Cr coating after 12 h of post-treatment with methanecontaining gas at 1000°C. 33. XRD coating phase evolution of a plasma-sprayed Cr coating after 6 and 12 h of posttreatment with methane-containing gas at 1000 °C. 34. SEM micrograph of coating porosity in a (a) plasma-sprayed Cr coating, (b) plasmasprayed Cr coating after 6 h of post-treatment with methane-containing gas at 1000 °C and (c) plasma-sprayed Cr coating after 12 h of post-treatment with methane-containing gas at 1000 °C. 35. XRD coating phase evolution of a cold-sprayed Cr coating after 6 and 12 h of posttreatment with methane-containing gas at 1000 °C. 36. SEM micrograph of coating porosity in a (a) cold-sprayed Cr coating, (b) cold-sprayed Cr coating after 6 h of post-treatment with methane-containing gas at 1000°C and (c) cold-sprayed Cr coating after 12 h of post-treatment with methane-containing gas at 1000°C.
Tribo-corrosion protection of valves and rotors using cermet layers applied with HVOF
Protection of Metals and Physical Chemistry of Surfaces, 2017
Protection of conventional steel parts in equipment that must withstand wear of the tribo-corrosion type (combination of heat and an aqueous medium) can be achieved by High Velocity Oxy-Fuel (HVOF) techniques, applying carbide-based cermet layers which decrease tribological and corrosion mechanisms. Three different carbide layers were applied to a ferritic-pearlitic steel in order to characterize properties such as sliding friction coefficient, phase identification, adhesion to the substrate, porosity, layer thickness and wear mechanisms. An example of a real rotatory equipment after a working campaign, both with and without protective layer is presented. The capacity of the protective layer to extend the life of parts like the one analyzed is evident even if zones of the layer are detached during the campaign.
Materials
This study is focused on the high-temperature corrosion evaluation of selected thermally sprayed coatings. NiCoCrAlYHfSi, NiCoCrAlY, NiCoCrAlTaReY, and CoCrAlYTaCSi coatings were sprayed on the base material 1.4923. This material is used as a cost-efficient construction material for components of power equipment. All evaluated coatings were sprayed using HP/HVOF (High-Pressure/High-Velocity Oxygen Fuel) technology. High-temperature corrosion testing was performed in a molten salt environment typical for coal-fired boilers. All coatings were exposed to the environment of 75% Na2SO4 and 25% NaCl at the temperature of 800 °C under cyclic conditions. Each cycle consisted of 1 h heating in a silicon carbide tube furnace followed by 20 min of cooling. The weight change measurement was performed after each cycle to establish the corrosion kinetics. Optical microscopy (OM), scanning electron microscopy (SEM), and elemental analysis (EDS) were used to analyze the corrosion mechanism. The CoC...
Protective coatings for very high temperature reactor applications
Materials and Corrosion, 2008
The future very high temperature reactors (VHTR) are nuclear systems that shall operate at a maximum temperature of about 950 8C. Primary circuit materials thus require good creep and corrosion resistance on very long time. Use of high-strength alloys with protective coatings could significantly improve the service life of high temperature reactor components. However, coating systems are mainly designed for shorter term purposes, often under extremely aggressive atmospheres, that cannot be extrapolated to the VHTR environment. We present our first investigations on the environmental resistance of Alloy 800H coated with two different protective systems under VHTR representative conditions: NiAl(Pt)/EBPVD ZrO 2 (Y) and NiCrAl(Y)/CVD ZrO 2 (Y). Isothermal exposures were carried out up to 1000 h at 950 8C in impure helium. This specific atmosphere was shown to induce formation of a surface oxide scale together with carburisation of the bare Alloy 800H. After high temperature exposure to impure helium, the microstructure of the coated specimens has changed due to both thermal ageing and corrosion. Performances of the two coating systems are compared regarding the VHTR application.
APPLICATIONS OF CERAMIC COATINGS AS TBCs ON THE INTERNAL COMBUSTION ENGINE VALVES
2018
Abstract: This study was started to see whether the use of thermal barrier coatings (TBC) can be extended to internal combustion engines using gasoline as fuel as to see the viability of other types of coatings with role of the thermal barrier than the usual zirconia. To this end, we covered three different types of powders on a set of valves, and then we tested them as close to reality as possible on a stand made up of a Dacia 1310 engine. It was noteworthy in the first instance that the exhaust gases resulted fall within the permissible limits, and after a while on the surface of the valve discs the specific tribofilm formed by the combustion residues is deposited together with a very fine film of carbon which continues to act by doubling the thermal barrier effect of the coating. Key words: ceramic coatings, TBC, valve discs, internal combustion gasoline engine.
Wear, 2006
The main objective of this paper is to study the slurry erosion and corrosion behavior of WC10Co4Cr, Armcore 'M' Stellite 6 and 12 HVOF coatings, TiAlN PVD coating, selected steels, such as X20Cr13, 17Cr-4Ni pH steel and Ti6Al4V titanium alloy alongwith conventional hard weld deposits of Stellite 6 and 21. The slurry erosion studies were carried out at 60 • angle of impingement for the velocities in the range of 15-20 m/s using mineral sand of −40 to +80 mesh. The corrosion studies were carried out as per ASTM B 117-73 for 100 h. During slurry erosion testing, WC10Co4Cr HVOF along with TiAlN PVD coating are found out, to be the best coating materials followed by HVOF coating of Armcore 'M' material. However, for corrosion, Ti6Al4V, Stellite 6 and 21 hard weld deposits and 17Cr-4Ni pH steel turned out to be the best materials followed by HVOF coating of Stellite 6 and 12. HVOF coatings of WC10Co4Cr and Armcore 'M' materials corroded significantly, however, TiAlN PVD coating corroded very badly even after 24 h of testing.
Journal of Thermal Spray Technology, 2018
The load-carrying capacity and wear resistance of a duplex-coated 316 stainless steel were determined, and a finite element numerical approach was developed to predict and corroborate experimental observations. Lowstrength alloys are generally used for highly demanding valve applications due to their superior chemical stability, galvanic corrosion resistance, and lower susceptibility to stress corrosion cracking failure. Hardfacing (using thermal spraying, laser cladding, or plasma transferred arc welding) is currently the most common solution to protect valve components. Hardfacing provides a thick, hardened case that significantly improves tribological performance. However, hardfaced layers provide lower wear resistance compared to vacuum-deposited hard coatings. One solution to further improve hardfacing performance is a duplex approach, which combines the two processes. This study investigates the following materials: a 316 stainless steel base hardfaced with laser-cladded Co-Cr superalloy and topped with a CVD nanostructured W-WC coating. Tribological properties of three configurations were assessed for their ability to delay initiation of plastic deformation and surface cracking under quasistatic loading and for their resistance to dry reciprocal sliding wear. The results demonstrate that finite element modeling allows numerical prediction and comparison of the load-carrying capacity and wear resistance of duplex-coated AISI 316 stainless steel. Keywords hybrid coating systems Á laser cladding Á load-carrying capacity Á mechanical modeling Á tribomechanical properties Á wear-resistant coatings