Sprayability and Properties of TiC-Ni Based Powders in the Detonation Gun and HVOF Processes

1997 ◽  
Author(s):  
P. Vuoristo ◽  
T. Mäntylä ◽  
L.-M. Berger ◽  
M. Nebelung
Keyword(s):  
Wear Test ◽  
Binder Content ◽  
Binder Phase ◽  
Coating Properties ◽  
X Ray Diffraction ◽  
Hvof Spraying ◽  
Hvof Process ◽  
Hvof Spray ◽  
Structures And Properties ◽  
Detonation Gun

Abstract Agglomerated and sintered TiC-Ni based powders were sprayed by detonation gun spray (DGS) and high-velocity oxy-fuel (HVOF) spray processes. Influence of the binder content (20 and 27 vol.-%) and some alloying elements, such as Mo, Co and N on the coating properties were investigated. The coating structures and properties were investigated by optical microscopy, hardness measurements, X-ray diffraction analysis and by rubber-wheel abrasion wear test. It was found that alloying the hard phase with Mo and N leads to an improvement of the coating properties. Alloying of the binder phase with Co did not affect the coating properties. Porosity in the powder granules was found to beneficial in order to melt more efficiently the particles in the DGS process and especially in the HVOF process. HVOF spraying of powders with the higher binder content of 27 vol.-% was found to be advantageous for the preparation of coatings with dense microstructures and good wear resistances.

Investigations on Thermal Spraying of Silicon Nitride-Based Powders

1998 ◽  
Author(s):  
L.-M. Berger ◽  
M. Herrmann ◽  
M. Nebelung ◽  
S. Thiele ◽  
R.B. Heimann ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Thermal Spraying ◽  
Wear Test ◽  
Atmospheric Plasma ◽  
Powder Injection ◽  
Binder Phase ◽  
X Ray Diffraction ◽  
Abrasion Wear ◽  
Detonation Gun ◽  
First Time

Abstract Thermal spraying of silicon nitride has been considered impossible because the high temperatures of the spray processes lead to its decomposition and oxidation. To suppress the degradation oxide bonded silicon nitride spray powders (OBSN) have been developed. In this paper spray experiments with these powders by detonation gun spraying (DGS) and atmospheric plasma spraying (APS) with axial powder injection are described. All coatings were characterized using optical microscopy and X-ray diffraction. In addition, DGS coatings were also investigated using SEM, microhardness testing and a rubber wheel abrasion wear test. For the first time, relatively dense Si3N4-rich coatings with an oxide binder phase were produced. The abrasion wear resistance of some DGS coatings was found to be sufficiently high to envisage industrial application. Further progress is expected from optimized spray experiments with variations of spray powder composition and particle size.

Production and Characterization of HVOF Sprayed NiCr-TiC Coatings Using SHS Powder Feedstock

2000 ◽  
Author(s):  
M.T. Blatchford ◽  
A.J. Horlock ◽  
D.G. McCartney ◽  
P.H. Shipway ◽  
J.V. Wood
Keyword(s):  
Thermal Spraying ◽  
Xrd Analysis ◽  
Powder Size ◽  
Coating Properties ◽  
X Ray Diffraction ◽  
Hvof Spraying ◽  
X Ray ◽  
Wear Rates ◽  
Powder Feedstock

Abstract In this paper, the production of NiCr-TiC powder by SHS, suitable for HVOF spraying, is discussed together with results on the microstructure and coating properties. Compacts for SHS were prepared by mixing elemental Ti and C with pre-alloyed Ni-20wt.% Cr powder to give an overall composition of 35wt.% NiCr and 65wt.% TiC. These were then ignited and a self-sustaining reaction proceeded to completion. Reacted compacts were crushed, sieved, and classified to give feedstock powders in size ranges of 10-45 µm and 45-75 µm. All powder was characterized prior to spraying based on particle size distribution, x-ray diffraction (XRD), and scanning electron microscopy (SEM/EDS). Thermal spraying was performed using both H2 and C3H6 as fuel gases in a UTP/Miller Thermal HVOF system. The resulting coatings were characterized by SEM and XRD analysis, and the microstructures correlated with powder size and spray conditions. Abrasive wear was determined by a modified 'dry sand rubber wheel' (DSRW) test and wear rates were measured. It has been found that wear rates comparable to those of HVOF sprayed WC-17wt% Co coatings can be achieved.

Obtention and Development of Blends of Powder to Obtain Free-Standing Components Produced by HVOF Spray-Forming

1998 ◽  
Author(s):  
J.M. Guilemany ◽  
J.M. De Paco ◽  
J.R. Miguel ◽  
J. Llibre
Keyword(s):  
Spray Forming ◽  
Homogeneous Distribution ◽  
Material Decomposition ◽  
Hvof Spraying ◽  
Free Standing ◽  
Hvof Process ◽  
Hvof Spray ◽  
Low Levels ◽  
Disk Test ◽  
Microstructural Examination

Abstract The feasibility of using the HVOF process for the thermal spray-forming of free-standing components has been investigated. HVOF spray forming offers a number of potential advantages compared to the established procedure of plasma forming, including increases in component density, and reduction in material decomposition during spraying. Using blends of carbide and superalloy powders in various proportions, HVOF spraying has been successfully used to form free-standing cylinders and cones of various lengths and thicknesses. Microstructural examination of the spray-formed material, using optical microscopy and scanning electron microscopy (SEM), has shown a homogeneous distribution of carbides in the superalloy matrix, with very low levels of porosity. Vickers microhardness has been measured on several sprayed forms. In order to complete the study of the different systems, abrasion (Rubber Wheel Test), friction (Ball on Disk Test) and erosion wear results have been obtained. These wear results have been used in order to evaluate the behaviour of the sprayed samples with a different powder percentage in the blends. Corrosion tests have been done to evaluate the corrosion resistance of the sprayed samples (ASTM D-1411).

Microstructure and Properties of Thermally Sprayed TiC-Ni and (Ti,Mo) C-NiCo Coatings

1996 ◽  
Author(s):  
P. Vuoristo ◽  
T. Stenberg ◽  
T. Mäntylä ◽  
L.-M. Berger ◽  
M. Nebelung
Keyword(s):  
Wear Test ◽  
Xrd Analysis ◽  
Binder Phase ◽  
Hard Phase ◽  
Wear Properties ◽  
Spray Detonation ◽  
Plasma Sprayed Coatings ◽  
Detonation Gun ◽  
Plasma Sprayed ◽  
Sprayed Coatings

Abstract Hardmetal-like coatings on the base of titanium carbide as a hard phase and nickel as a metal binder were prepared from agglomerated and sintered powders by plasma spray, detonation gun spray and high-velocity oxygen-fuel spray processes. The powders used in the spray experiments were plain TiC-Ni type and alloyed (Ti,Mo)C-NiCo type powders with different binder content. The coatings were characterized by optical and scanning electron microscopy, microhardness measurements, XRD analysis and in an abrasion wear test. The results showed that the sprayability of these novel hardmetal-like powders is good in all spray processes studied and the coatings deposited were found to have dense microstructures and good properties. The XRD analysis showed that the coatings have a phase structure similar to that found in the spray powder. The amount of retained carbides in the coatings was high. Some regions in which the carbides had dissolved with the metallic binder phase during spraying were also found, especially in plasma sprayed coatings. In such microstructural regions submicron size reprecipitated carbides were detected. These were clearly detectable in detonation gun sprayed coatings. HVOF sprayed coatings were found to contain a very high content of retained carbide phase. In this process the heat effect to the material seemed to be the lowest. The wear tests clearly showed the importance of alloying the hard phase and the binder phase in order to improve the wear resistance of the coatings. All studied spray processes produced coatings with nearly similar coating wear properties.

Microstructure and wear resistance of Cuss-toughened Cr5Si3/CrSi metal silicide alloys

2005 ◽  
Vol 20 (5) ◽  
pp. 1122-1130 ◽  
Author(s):  
Y.X. Yin ◽  
H.M. Wang
Keyword(s):  
Solid Solution ◽  
Wear Resistance ◽  
Sliding Wear ◽  
Room Temperature ◽  
Wear Test ◽  
Melting Process ◽  
Dry Sliding Wear ◽  
Metal Silicide ◽  
X Ray Diffraction ◽  
X Ray

Wear-resistant Cu-based solid-solution-toughened Cr5Si3/CrSi metal silicide alloy with a microstructure consisting of predominantly the dual-phase primary dendrites with a Cr5Si3 core encapsulated by CrSi phase and a small amount of interdendritic Cu-based solid solution (Cuss) was designed and fabricated by the laser melting process using Cr–Si–Cu elemental powder blends as the precursor materials. The microstructure of the Cuss-toughened Cr5Si3/CrSi metal silicide alloy was characterized by optical microscopy, powder x-ray diffraction, and energy dispersive spectroscopy. The Cuss-toughened silicide alloys have excellent wear resistance and low coefficient of friction under room temperature dry sliding wear test conditions with hardened 0.45% C carbon steel as the sliding–mating counterpart.

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.

Microstructure and Properties of TiC-CrNiMo SHS Spray Powder and Thermally Sprayed Coating

2000 ◽  
Author(s):  
M. Väisänen ◽  
P. Vuoristo ◽  
T. Mäntylä ◽  
V. Maunu ◽  
P. Lintunen ◽  
...  
Keyword(s):  
Particle Size ◽  
Corrosion Behaviour ◽  
Metallic Matrix ◽  
Electrochemical Corrosion ◽  
Wear Test ◽  
Spherical Shape ◽  
Open Circuit ◽  
Hvof Spraying ◽  
Particle Size Range ◽  
Abrasion Wear

Abstract Titanium carbide cermet spray powder was produced by the SHS process (Self-propagating High-temperature Synthesis) using elemental Ti, C, Mo and prealloyed CrNiMo powders as starting materials. The powder was characterised (particle size distribution, phase structure, morphology) and the internal structure of each cermet particle was found out to be dense consisting of fine distribution of carbides embedded in a metallic matrix. The particle size range suitable for thermal spraying was obtained by sieving and air classifying. The coatings were prepared by HVOF spraying (DJH2600 and DJH2700). The dry abrasion wear resistance was evaluated by the rubber wheel abrasion wear test and electrochemical corrosion behaviour by open circuit potential measurements. According to the XRD analysis the amount of retained carbides in the coatings is high and the carbide phase has a spherical shape also in the coatings. The microstructure of coatings obtained is dense and the coatings possess good properties in wear and corrosion tests. WC-Co-Cr and Cr3C2-NiCr powders were used for comparison.

Thermal Spray Forming Using the HVOF Technique

1997 ◽  
Author(s):  
J.M. Guilemany ◽  
J.R. Miguel ◽  
M.J. Dougan ◽  
J.M. de Paco ◽  
Z. Dong ◽  
...  
Keyword(s):  
Thermal Spray ◽  
Spray Forming ◽  
Homogeneous Distribution ◽  
Material Decomposition ◽  
Hvof Spraying ◽  
Free Standing ◽  
Hvof Spray ◽  
The Matrix ◽  
Low Levels ◽  
Microstructural Examination

Abstract The feasibility of using the HVOF process for the thermal spray-forming of free-standing components has been investigated. HVOF spray forming offers a number of potential advantages compared to the established procedure of plasma forming, including increases in component density, and reduction in material decomposition during spraying. Using blends of carbide and superalloy powders in various proportions, HVOF spraying has been successfully used to form free-standing cylinders and cones of various lengths and thicknesses. Microstructural examination of the spray-formed material has shown a homogeneous distribution of carbides in the superalloy matrix, with very low levels of porosity. Refinement of the procedure has allowed reduction of the matrix content, and the forming of fragile materials.

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.

Effect of WC Addition on Phase Formation and Microstructure of TiC-Ni Composites

2008 ◽  
Vol 55-57 ◽  
pp. 353-356
Author(s):  
Nawarat Wora-uaychai ◽  
Nuchthana Poolthong ◽  
Ruangdaj Tongsri
Keyword(s):  
Liquid Phase ◽  
Tungsten Carbide ◽  
Phase Formation ◽  
Liquid Phase Sintering ◽  
Precipitation Process ◽  
Solid Solution Phase ◽  
Binder Phase ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
X Ray

In this research, titanium carbide-nickel (TiC-Ni) composites, with tungsten carbide addition, were fabricated by using a powder metallurgy technique. The TiC-Ni mixtures containing between 0-15 wt. % tungsten carbide (WC), were compacted and then sintered at 1300°C and 1400°C, respectively. The phase formation and microstructure of the WC-added TiC-Ni composites have been investigated by X-ray diffraction and scanning electron microscopy techniques. Mechanical properties of these composites were assessed by an indentation technique. The X-ray diffraction patterns showed no evidence of tungsten rich phases in the sintered WC-added cermets. This indicates that during the sintering process, tungsten carbide particles were dissolved in metallic binder phase (Ni phase) via dissolution/re-precipitation process during liquid phase sintering. The liquid phase formed during sintering process could improve sinterability of TiC-based cermets i.e., it could lower sintering temperatures. The TiC-Ni composites typically exhibited a core-rim structure. The cores consisted of undissolved TiC particles enveloped by rims of (Ti, W)C solid solution phase. Hardness of TiC-Ni composites increased with WC content. Sintering temperature also had a slight effect on hardness values.

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