scholarly journals Precipitation Hardening of the HVOF Sprayed Single-Phase High-Entropy Alloy CrFeCoNi

Coatings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 701
Author(s):  
Martin Löbel ◽  
Thomas Lindner ◽  
Ralph Hunger ◽  
Robin Berger ◽  
Thomas Lampke
Keyword(s):  
Wear Resistance ◽  
Single Phase ◽  
High Entropy Alloy ◽  
High Entropy ◽  
Thermal Spray Process ◽  
Spray Process ◽  
Production Route ◽  
Hvof Thermal Spray ◽  
Material Usage ◽  
Hvof Thermal Spray Process

The application of high-entropy alloys (HEA) in surface technology has great potential due to the high corrosion and wear resistance. A further improvement can be achieved by applying thermochemical treatments. Powder-pack boriding enables the formation of a protective precipitation layer. This process has already been applied for cast HEAs causing the formation of a diffusion-enriched surface layer and a distinct increase in wear resistance. In the current investigations, the alloy CrFeCoNi with a single-phase face-centred cubic (fcc) structure is considered. An efficient application can be achieved by limiting the material usage of HEAs to the surface. Therefore, the high-velocity-oxygen-fuel (HVOF) thermal spray process is applied. Boriding was conducted with an adapted powder-pack routine. Furthermore, borided bulk HEAs were considered as a reference. The influence of the production route and boriding treatment on the microstructure, phase formation, and properties was investigated in detail. For the coating and the cast HEA, a precipitation layer is formed. Hence, the hardness and wear resistance are significantly increased. The current study proves the suitability of the investigated process combination.

scholarly journals Enhanced Wear Behaviour of Spark Plasma Sintered AlCoCrFeNiTi High-Entropy Alloy Composites

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2225 ◽  
Author(s):  
Martin Löbel ◽  
Thomas Lindner ◽  
Thomas Lampke
Keyword(s):  
Wear Resistance ◽  
High Hardness ◽  
Solid Lubricants ◽  
Wear Behaviour ◽  
High Entropy Alloy ◽  
Surface Protection ◽  
High Entropy ◽  
Production Route ◽  
The Coefficient Of Friction ◽  
Spark Plasma

High hardness and good wear resistance have been revealed for the high-entropy alloy (HEA) system AlCoCrFeNiTi, confirming the potential for surface protection applications. Detailed studies to investigate the microstructure and phase formation have been carried out using different production routes. Powder metallurgical technologies allow for much higher flexibility in the customisation of materials compared to casting processes. Particularly, spark plasma sintering (SPS) enables the fast processing of the feedstock, the suppression of grain coarsening and the production of samples with a low porosity. Furthermore, solid lubricants can be incorporated for the improvement of wear resistance and the reduction of the coefficient of friction (COF). This study focuses on the production of AlCoCrFeNiTi composites comprising solid lubricants. Bulk materials with a MoS2 content of up to 15 wt % were produced. The wear resistance and COF were investigated in detail under sliding wear conditions in ball-on-disk tests at room temperature and elevated temperature. At least 10 wt % of MoS2 was required to improve the wear behaviour in both test conditions. Furthermore, the effects of the production route and the content of solid lubricant on microstructure formation and phase composition were investigated. Two major body-centred cubic (bcc) phases were detected in accordance with the feedstock. The formation of additional phases indicated the decomposition of MoS2.

Influence of HVOF Thermal Spray Process on the Microstructures and Properties of Fe-Based Amorphous / Nano Metallic Coatings

2009 ◽  
Vol 633-634 ◽  
pp. 685-694 ◽  
Author(s):  
X.Q. Liu ◽  
Y.G. Zheng ◽  
X.C. Chang ◽  
W.L. Hou ◽  
Jian Qiu Wang
Keyword(s):  
High Performance ◽  
Good Alternative ◽  
Metallic Coating ◽  
Thermal Spray Process ◽  
Spray Process ◽  
Hvof Thermal Spray ◽  
Alternative Material ◽  
High Microhardness ◽  
Coating Microstructure ◽  
Hvof Thermal Spray Process

A new Fe-based amorphous / nano metallic coating with a good combination of high microhardness and excellent erosion corrosion resistance was produced by high velocity oxygen fuel (HVOF). The coating microstructure, amorphous phase content and properties under different HVOF processes were evaluated. It was found that they are very sensitive to the powder feed rate, stand-off distance and oxygen flow. This high performance amorphous / nano metallic coating could be applied as a good alternative material in erosion and corrosion environments.

Numerical analysis of flame and particle behavior in an HVOF thermal spray process

2016 ◽  
Vol 96 ◽  
pp. 370-376 ◽  
Author(s):  
Jiajing Pan ◽  
Shengsun Hu ◽  
Lijun Yang ◽  
Kunying Ding ◽  
Baiqing Ma
Keyword(s):  
Numerical Analysis ◽  
Thermal Spray ◽  
Thermal Spray Process ◽  
Particle Behavior ◽  
Spray Process ◽  
Hvof Thermal Spray ◽  
Hvof Thermal Spray Process

HVOF Thermal Spray Alternative for Hard Chrome Plating Process

2016 ◽  
Vol 1138 ◽  
pp. 139-146 ◽  
Author(s):  
Ioan Aurel Perianu
Keyword(s):  
Thermal Spray ◽  
Commercial Production ◽  
Chrome Plating ◽  
Thermal Spray Process ◽  
Spray Process ◽  
Hvof Thermal Spray ◽  
Hard Chrome ◽  
Hvof Thermal Spray Process ◽  
Critical Process

Hard chrome plating is a process that has been in commercial production for over 50 years and which is a critical process associated with manufacturing and maintenance of parts in the industries. The paper presents aspects regarding the use of HVOF thermal spray process as an alternative for hard chrome plating.

A Gas Shroud Nozzle for HVOF Spray Deposition

1998 ◽  
Author(s):  
V. Pershin ◽  
J. Mostaghimi ◽  
S. Chandra ◽  
T. Coyle
Keyword(s):  
Spray Deposition ◽  
Large Reduction ◽  
Appreciable Change ◽  
Thermal Spray Process ◽  
Spray Process ◽  
Hvof Thermal Spray ◽  
Hvof Spray ◽  
Standard Configuration ◽  
Gas Shroud ◽  
Hvof Thermal Spray Process

Abstract Properties of MCrAIY coatings obtained by High Velocity Oxy-Fuel (HVOF) thermal spray process operated in a standard configuration were compared with those obtained using a gas shroud attachment to the HVOF gun. Our measurements show that the attached gas (nitrogen) shroud nozzle considerably reduces the oxygen content in the coating without an appreciable change in the microstructure. The particle temperatures were decreased by an average of 100 C at a standoff distance of 0.275 m (11 inches). There was also a large reduction in the particle velocity at this distance. Both these effects were related to the excessive amount of nitrogen used for shrouding.

scholarly journals Development of a semi automated dual feed unit to produce FGM coatings using the HVOF thermal spray process

2014 ◽  
Vol 32 (1) ◽  
pp. 18
Author(s):  
K.A. Mamun ◽  
J. Stokes
Keyword(s):  
Thermal Spray ◽  
Functionally Graded ◽  
Chemical Compositions ◽  
Thermal Spray Process ◽  
Spray Process ◽  
Powder Feed ◽  
Hvof Thermal Spray ◽  
Graded Coatings ◽  
Thick Coatings ◽  
Hvof Thermal Spray Process

The application of functionally graded materials (FGMs) is quite difficult, but thermal spray processes like Plasma spray have demonstrated their unique potential in producing graded deposits, where researchers have used twin powder feed systems to mix different proportions of powders. FGMs vary in composition and/or microstructure from one boundary (substrate) to another (top service surface), and innovative characteristics result from the gradient from metals to ceramics or non-metallic to metals. The present study investigates an innovative modification of a high velocity oxy-fuel (HVOF) thermal spray process to produce functionally graded thick coatings. In order to deposit thick coatings, certain problems have to be overcome. Graded coatings enable gradual variation of the coating composition and/or microstructure, which offers the possibility of reducing residual stress build-up with in coatings. In order to spray such a coating, modification to a commercial powder feed hopper was required to enable it to deposit two powders simultaneously which allows deposition of different layers of coating with changing chemical compositions, without interruption to the spraying process. Various concepts for this modification were identified and one design was selected, having been validated through use of a process model, developed using ANSYS Flotran finite element analysis. In the current research the mixing of different proportions of powders were controlled by a computer using LabVIEW software and hardware, which allowed the control and repeatability of the microstructure when producing functionally graded coatings.

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