Potential of Suspension Spraying for Development of Dense WC-12Co Coatings

2021 ◽  
Author(s):  
Filofteia-Laura Toma ◽  
Oliver Kunze ◽  
Anja Meyer ◽  
Annegret Potthoff ◽  
Markus Mayer ◽  
...  
Keyword(s):  
Suspension Spraying ◽  
Hvof Spraying ◽  
Hvof Process ◽  
Carbide Coatings ◽  
Water Based ◽  
Near Net Shape ◽  
Heavy Loads ◽  
Thermally Sprayed ◽  
Spraying Process

Abstract Thermally sprayed WC-Co coatings provide excellent wear resistance and corrosion protection under heavy loads, but their application usually involves additional grinding and polishing steps, which can be 3-4 times costlier than the spraying process itself. There is thus the motivation to develop a process that produces smooth, near-net-shape carbide coatings. This contribution is an investigation of WC-12Co coatings obtained by suspension HVOF spraying. Significant work was devoted to the development and characterization of water-based hardmetal suspensions synthesized from commercially available WC and Co powders. The suspensions produced were sprayed using the HVOF process, and the resulting coatings were evaluated based on microstructure, hardness, and phase composition.

INFLUENCE OF CARBON NANOTUBES REINFORCEMENT ON CHARACTERISTICS OF THERMALLY SPRAYED CERAMIC COATINGS

2020 ◽  
pp. 2050052
Author(s):  
G. MOHAMMED THALIB BASHA ◽  
B. VENKATESHWARLU
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Ceramic Coatings ◽  
Air Plasma ◽  
Air Plasma Spraying ◽  
Hvof Spraying ◽  
Titania Coatings ◽  
Thermally Sprayed ◽  
Spraying Process ◽  
Reduced Surface

The influence of reinforcement of carbon nanotubes (CNTs) on microstructural features and mechanical properties of thermally sprayed Al2O3–3[Formula: see text]wt.%TiO2 and WC–20[Formula: see text]wt.%Co coatings was investigated. Alumina–Titania coatings were deposited by Air Plasma Spraying (APS) and Tungsten Carbide–Cobalt coatings were deposited by High-Velocity Oxy-Fuel (HVOF) spraying process. The coatings obtained with reinforcement of CNTs were characterized to interpret the microstructural changes and also to evaluate the variation in their mechanical properties. The percentage composition of CNTs in both APS and HVOF coatings systems were varied in the order of 2, 4, and 6[Formula: see text]wt.%. It has been found that homogenous dispersion of carbon nanotubes in the coating systems results in increased microhardness and reduced surface roughness. Also, the microstructural features of the coating systems clearly showed that the coatings are denser with fewer pores due to the presence of CNTs.

Near-Net-Shape and Dense Wear Resistant Thermally Sprayed Coatings

2008 ◽  
Vol 384 ◽  
pp. 117-123
Author(s):  
Wolfgang Tillmann ◽  
Evelina Vogli ◽  
Ingor Baumann ◽  
Benjamin Krebs
Keyword(s):  
Deep Drawing ◽  
Thermal Spraying ◽  
High Strength Steels ◽  
High Strength ◽  
Thermally Sprayed Coatings ◽  
Near Net Shape ◽  
Forming Tools ◽  
Thermally Sprayed ◽  
Sprayed Coatings ◽  
Spraying Process

Deep drawing of high strength steels imposes high tribological requirements on forming tools. Thermal spraying is regarded as a promising technology to improve the tool’s performance and the service life of the forming tool, as long as ambitious demands of the coating process are matched. In order to qualify a thermal spraying process for a surface technology in deep drawing it is crucial that the coating obtains an extremely dense structure and a smooth, near-net-shape surface. The study presented considers two different approaches to achieve those goals. The application of fine-scaled powders (<10$m) spraying through HVOF technique offers the opportunity to deposit dense coatings with very smooth surfaces. In contrast, it is also feasible to achieve very smooth and dense coatings by combining conventional powders with a subsequently densification procedure

Analysis of Microstructural Changes with Temperature of Thermally Sprayed WC-Co Coatings by Mechanical Spectroscopy

2012 ◽  
Vol 184 ◽  
pp. 313-318 ◽  
Author(s):  
Daniele Mari ◽  
L.M. Berger ◽  
S. Stahr
Keyword(s):  
Elastic Modulus ◽  
Sudden Increase ◽  
X Ray Diffraction ◽  
Mechanical Spectroscopy ◽  
Hvof Spraying ◽  
Mechanical Parts ◽  
Spark Erosion ◽  
Temperature Scanning ◽  
First Time ◽  
Thermally Sprayed

Thermally sprayed hardmetal coatings can be used to improve the wear or fatigue resistance of mechanical parts. Depending on the deposition conditions, their microstructure and phase composition are out of equilibrium at different levels due to the extreme heating/cooling rates. In the present study, the changes that occur with temperature variation are monitored by mechanical spectroscopy. Requirements to specimen of mechanical spectroscopy created the need to prepare WC-17%Co coatings of 1.2 mm thickness by high velocity oxy-fuel (HVOF) spraying. The coatings, separated from the substrate by spark erosion, were tested in a forced torsion pendulum between room temperature and 1570 K at a temperature scanning rate of 1K/min. The mechanical loss spectrum shows different features. At 800 K, a maximum M1 is observed in coincidence with a sudden increase of the elastic modulus. The change of the elastic modulus is due to a densification of the material possibly related to cobalt recrystallization. A relaxation peak located at about 1100 K is typically found in WC-Co hardmetals. It is attributed to the movement of dislocations in the cobalt phase. A sharp peak is observed at 1510 K on heating and at 1410 K on cooling. Such peak is due to the reversible transition from W3Co3C at high temperature to W6Co6C at low temperature as proven by X-ray diffraction. The reversibility of such transformation was observed for the first time.

Characterization of WC-Co Coatings Using HP/HVOF Process

1996 ◽  
Author(s):  
S.Y. Hwang ◽  
B.G. Seong ◽  
M.C. Kim
Keyword(s):  
Wear Resistance ◽  
X Ray Diffraction ◽  
High Carbon ◽  
Properties Of Coatings ◽  
X Ray ◽  
Hvof Process ◽  
Number Of Passes ◽  
Oxygen Fuel

Abstract To maintain surface roughness of process rolls in cold rolling steel plants, WC-Co coatings have been known to be effective ones. In this study, a high pressure/high velocity oxygen fuel (HP/HVOF) process was used to obtain WC-Co coatings. To get the best quality of coatings, WC-Co coatings are sprayed with numerous powders made by various processes. These powders include agglomerated sintered powders, fused-crushed powders, extra high carbon WC-Co powders and (W2C, WC)-Co powders. After spraying, properties of coatings such as hardness, wear resistance. X-ray diffraction, and microstructures were analyzed. For coatings produced by agglomerated-sintered powders, hardness of the coating increased as power levels and the number of passes were increased. In case of the coatings produced by fused-crushed powders, a very low deposition rate was obtained due to a low flowablity of the powders. In addition, the WC-Co coatings sprayed with extra carbon content of WC-Co did not show improved hardness and wear resistance. Also, some decomposition of WC was observed in the coating. Finally, the coatings produced by (W2C, WC)-Co powders produced higher hardness and lower wear resistance coating.

Studies of the Flame Spraying of Polymers

1996 ◽  
Author(s):  
D.J. Varacalle ◽  
K.W. Couch ◽  
V.S. Budinger
Keyword(s):  
Bond Strength ◽  
Combustion Process ◽  
Experimental Studies ◽  
Polymer Coatings ◽  
Flame Spraying ◽  
Knoop Microhardness ◽  
Resultant Coating ◽  
Strength Characterization ◽  
Thermally Sprayed

Abstract Experimental studies of the subsonic combustion process have been conducted in order to determine the quality and economics of polyester, epoxy, urethane, and hybrid polyester-epoxy coatings. Thermally sprayed polymer coatings are of interest to several industries for anti-corrosion applications, including the infrastructural, chemical, automotive, and aircraft industries. Classical experiments were conducted, from which a substantial range of thermal processing conditions and their effect on the resultant coating were obtained. The coatings were characterized and evaluated by a number of techniques, including Knoop microhardness tests, optical metallography, image analysis, and bond strength. Characterization of the coatings yielded thickness, bond strength, hardness, and porosity.

scholarly journals Characterization of water based nanofluid for quench medium

2018 ◽  
Vol 348 ◽  
pp. 012009 ◽  
Author(s):  
Kresnodrianto ◽  
S. Harjanto ◽  
W.N. Putra ◽  
G. Ramahdita ◽  
S.S. Yahya ◽  
...  
Keyword(s):  
Water Based ◽  
Quench Medium

Mechanical Design for Accuracy of Linkage Servo Press for Near-Net Shape Forming

2018 ◽  
Author(s):  
Jing Tao ◽  
Huanan Qian ◽  
Suiran Yu
Keyword(s):  
Mechanical Design ◽  
Structure Design ◽  
Tolerance Allocation ◽  
Component Level ◽  
Eccentric Load ◽  
Servo Press ◽  
Near Net Shape ◽  
Net Shape Forming ◽  
Heavy Loads

The accuracy of machine is important to achieving highly accurate shapes. This paper is focused on mechanical design of highly accurate mechanical linkage servo press applicable to (near-)net shape forming. The effects of geometric errors, deformations under heavy loads and ram tilting are analyzed. A top-down design for accuracy approach is proposed: First, accuracy model for identification of inaccuracy-causing factors and their interlinking relations is developed. Then, based on this model, top accuracy index are decomposed and translated into structure design specifications at component level. Both analytic and simulation methods are employed for design for accuracy in aspects of dimensional and geometric tolerance allocation, stiffness synthesis and anti-eccentric load capability. A case study of mechanical design for accuracy of a six-linkage mechanical servo press is also presented to demonstrate and test the proposed design approaches.

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