Special Issue "Innovative Technologies and Materials for the Production of Mechanical, Thermal and Corrosion Wear-Resistant Surface Layers and Coatings"

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Manufacturing Processes and Systems".

Deadline for manuscript submissions: 20 June 2022.

Special Issue Editors

Dr. Artur Czupryński
E-Mail Website
Guest Editor
Department of Welding Engineering, Faculty of Mechanical Engineering, Silesian University of Technology, Konarskiego 18A Str., 44-100 Gliwice, Poland
Interests: welding; hardfacing; thermal spraying; explosive cladding process; brazing welding; surface engineering; abrasive wear; erosive wear; anti-corrosion protection methods
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Claudio Mele
E-Mail Website
Guest Editor
Department of Engineering for Innovation, University of Salento, Via Monteroni, 73100 Lecce, Italy
Interests: degradation of materials for batteries; Zn-air batteries; corrosion; electrochemical applications; spectroelectrochemistry
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Surface deterioration is a very real problem in many industries. Intensive wear of machine and apparatus parts in mining, quarrying, petrochemical, metallurgical, cement, construction, power generation, and many more industries is driving the increasing demand for innovative materials and technologies for the production of surface layers and coatings that are increasingly durable. Periodically occurring failures of machine elements caused by impact, abrasive, erosion, compression, cavitation, adhesive, corrosion wear, oxidation, thermal shock, or a combination of these leads to economic losses in the form of unplanned production downtime and are associated with the frequent requirement for replacement of parts and, in extreme cases, loss of health and life. During the wear process, the surface layer of material is degraded and damaged by mechanical, high temperature, or chemical reaction between the worn element and other elements or aggressive environments. During the prolonged wear process, weight loss and change of dimensions and shape of the subjected part are observed. These processes are observed under conditions of surface contact with metals, nonmetals, solid or liquid particles in a liquid medium, and flow of liquids. Wear intensity is a function of wear type, process parameters, and surface layer resistance. In principle, wear is the main factor influencing the reliability and durability of machines and products.

The effects of wear can be repaired using, among other things, welding technologies. Surfacing, coating, cladding, thermal spraying, galvanization processes with specialized welding filler materials are used to replace worn metal with metal that can provide more satisfactory wear resistance than the original. These technologies are also applied for the purpose of reducing wear or loss of material by abrasion, impact, erosion, oxidation, cavitation, corrosion, etc.

Many of the abovementioned types of wear occur in conjunction with others. It is wise to consider not only one factor but to look for a combination of factors that create the wear problem in order to determine the best type of surfacing material to apply. This is achieved by studying the worn part, the job it does, how it works with other parts of the equipment, and the environment in which it works. With these factors in mind, it is then possible to make a decision regarding selection of surfacing, plating, spraying, or galvanizing alloy. In order to properly select an alloy for a specific requirement, it is necessary to understand the wear phenomena that have occurred. Wear prediction proves to be difficult due not only to the dependence on material and design properties but also on difficulties in the quantification and control of tribological systems during the lifetime.

The purpose of this Special Issue is to present the latest developments in the field of research on innovative technologies and materials to produce surface layers and coatings resistant to mechanical wear, thermal wear, and corrosion.

The main topics of interest include but are not limited to the following:

  • the study of modern welding technologies to produce surface layers and clads resistant to mechanical wear, thermal wear, and corrosion;
  • the study of modern thermal spraying technologies to produce coatings resistant to mechanical wear, thermal wear, and corrosion;
  • the study of modern braze cladding technologies to produce clads resistant to corrosion;
  • the study of modern anticorrosion protection methods to produce coatings resistant to corrosion;
  • the study of structure and mechanical properties of surface layers, coatings, and clads produced on metal substrate;
  • the study of wear mechanisms of surface layers, coatings, and clads resistant to mechanical wear, thermal wear, and corrosion;
  • the characterization of materials to produce surface layers and coatings resistant to mechanical wear, thermal wear, and corrosion;
  • the characterization techniques for the innovative surface layers and coatings;
  • the study of improved economics of production surface layers, coatings, and clads resistant to mechanical wear, thermal wear, and corrosion.

Dr. Artur Czupryński
Prof. Dr. Claudio Mele
Guest Editors

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2300 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • welding
  • surfacing
  • hardfacing
  • cladding
  • spraying
  • wear
  • erosion
  • abrasion
  • corrosion

Published Papers (12 papers)

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Research

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Article
The Phenomena and Criteria Determining the Cracking Susceptibility of Repair Padding Welds of the Inconel 713C Nickel Alloy
Materials 2022, 15(2), 634; https://doi.org/10.3390/ma15020634 - 14 Jan 2022
Viewed by 72
Abstract
The creep-resistant casting nickel alloys (e.g., Inconel 713C) belong to the group of difficult-to-weld materials that are using for precise element production; e.g., aircraft engines. In precision castings composed of these alloys, some surface defects can be observed, especially in the form of [...] Read more.
The creep-resistant casting nickel alloys (e.g., Inconel 713C) belong to the group of difficult-to-weld materials that are using for precise element production; e.g., aircraft engines. In precision castings composed of these alloys, some surface defects can be observed, especially in the form of surface discontinuities. These defects disqualify the castings for use. In this paper, the results of technological tests of remelting and surfacing by the Tungsten Inert Gas method (TIG) in an argon shield and TecLine 8910 gas mixture are presented for stationary parts of aircraft engines cast from Inconel 713C alloy. Based on the results of metallographic studies, it was found that the main problem during remelting and pad welding of Inconel 713C castings was the appearance of hot microcracks. This type of defect was initiated in the partial melting zone, and propagated to the heat affected zone (HAZ) subsequently. The transvarestraint test was performed to determine the hot-cracking criteria. The results of these tests indicated that under the conditions of variable deformation during the remelting and pad welding process, the high-temperature brittleness range (HTBR) was equal 246 °C, and it was between 1053 °C and 1299 °C. In this range, the Inconel 713C was prone to hot cracking. The maximum deformation for which the material was resistant to hot cracking was equal to 0.3%. The critical strain speed (CSS) of 1.71 1/s, and the critical strain rate for temperature drop (CST), which in this case was 0.0055 1/°C, should be used as a criteria for assessing the tendency for hot cracking of the Inconel 713C alloy in the HTBR. The developed technological guidelines and hot-cracking criteria can be used to repair Inconel 713C precision castings or modify their surfaces using welding processes. Full article
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Article
Effect of Microstructure and Hardness on Cavitation Erosion and Dry Sliding Wear of HVOF Deposited CoNiCrAlY, NiCoCrAlY and NiCrMoNbTa Coatings
Materials 2022, 15(1), 93; https://doi.org/10.3390/ma15010093 - 23 Dec 2021
Viewed by 288
Abstract
Metallic coatings based on cobalt and nickel are promising for elongating the life span of machine components operated in harsh environments. However, reports regarding the ambient temperature tribological performance and cavitation erosion resistance of popular MCrAlY (where M = Co, Ni or Co/Ni) [...] Read more.
Metallic coatings based on cobalt and nickel are promising for elongating the life span of machine components operated in harsh environments. However, reports regarding the ambient temperature tribological performance and cavitation erosion resistance of popular MCrAlY (where M = Co, Ni or Co/Ni) and NiCrMoNbTa coatings are scant. This study comparatively investigates the effects of microstructure and hardness of HVOF deposited CoNiCrAlY, NiCoCrAlY and NiCrMoNbTa coatings on tribological and cavitation erosion performance. The cavitation erosion test was conducted using the vibratory method following the ASTM G32 standard. The tribological examination was done using a ball-on-disc tribometer. Analysis of the chemical composition, microstructure, phase composition and hardness reveal the dry sliding wear and cavitation erosion mechanisms. Coatings present increasing resistance to both sliding wear and cavitation erosion in the following order: NiCoCrAlY < CoNiCrAlY < NiCrMoNbTa. The tribological behaviour of coatings relies on abrasive grooving and oxidation of the wear products. In the case of NiCrMoNbTa coatings, abrasion is followed by the severe adhesive smearing of oxidised wear products which end in the lowest coefficient of friction and wear rate. Cavitation erosion is initiated at microstructure discontinuities and ends with severe surface pitting. CoNiCrAlY and NiCoCrAlY coatings present semi brittle behavior, whereas NiCrMoNbTa presents ductile mode and lesser surface pitting, which improves its anti-cavitation performance. The differences in microstructure of investigated coatings affect the wear and cavitation erosion performance more than the hardness itself. Full article
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Article
Microstructure Investigation of WC-Based Coatings Prepared by HVOF onto AZ31 Substrate
Materials 2022, 15(1), 40; https://doi.org/10.3390/ma15010040 - 22 Dec 2021
Viewed by 315
Abstract
In this paper, three commercial cermet powders, WC-Co-Cr, WC-Co and WC-Cr3C2-Ni, were sprayed by the High Velocity Oxy Fuel (HVOF) method onto magnesium alloy AZ31 substrate. The coatings were investigated in terms of their microstructure, phase analysis and residual [...] Read more.
In this paper, three commercial cermet powders, WC-Co-Cr, WC-Co and WC-Cr3C2-Ni, were sprayed by the High Velocity Oxy Fuel (HVOF) method onto magnesium alloy AZ31 substrate. The coatings were investigated in terms of their microstructure, phase analysis and residual stress. The manufactured coatings were analyzed extensively using optical microscopy (OM), X-ray diffraction (XRD), scanning (SEM) and transmission electron microscopy (TEM). Based on microstructure studies, it was noted that the coatings show satisfactory homogeneity. XRD analysis shows that in WC-Co, WC-Co-Cr and WC-Cr3C2-Ni coatings, main peaks are related to WC. Weaker peaks such as W2C, Co0.9W0.1, Co and W for WC-Co and W2C, Cr3C2 and Cr7C3 for WC-Cr3C2-Ni also occur. In all cermet coatings, linear stress showed compressive nature. In WC-Co and WC-Cr3C2-Ni, residual stress had a similar value, while in WC-Co-Cr, linear stress was lower. It was also proved that spraying onto magnesium substrate causes shear stress in the WC phase, most likely due to the low elastic modulus of magnesium alloy substrate. Full article
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Article
Comparative Analysis of the Phase Interaction in Plasma Surfaced NiBSi Overlays with IVB and VIB Transition Metal Carbides
Materials 2021, 14(21), 6617; https://doi.org/10.3390/ma14216617 - 03 Nov 2021
Cited by 1 | Viewed by 370
Abstract
Important applications of transition metal carbides (TMCs) are as wear resistant composite layers deposited by plasma transferred arc welding (PTAW) and laser methods. Growing interest in them has also been observed in additive manufacturing and in HEA technology (bulk composite materials and layers), [...] Read more.
Important applications of transition metal carbides (TMCs) are as wear resistant composite layers deposited by plasma transferred arc welding (PTAW) and laser methods. Growing interest in them has also been observed in additive manufacturing and in HEA technology (bulk composite materials and layers), and in the area of energy conversion and storage. This paper presents the results of comparative studies on interfacial interactions in the NiBSi−TMCs system for two border IVB and VIB TM groups of the periodic table. Model (wettability and spreadability) and application experiments (testing of the PTAW-obtained carbide particle−matrix boundaries) were performed. Fe from partially melted steel substrates is active in the liquid NiBSi−TMCs system. It was revealed that the interaction of TMCs with the liquid NiBSi matrix tends to increase with the group number, and from the top to bottom inside individual groups. Particles of IVB TMCs are decomposed by penetration of the liquid along the grain boundaries, whereas those of VIB are decomposed by solubility in the matrix and secondary crystallization. No transition zones formed at the interfacial boundaries of the matrix−IVB group TMCs, unlike in the case of the VIB group. The experimental results are discussed using the data on the TMC electronic structure and the physicochemical properties. Full article
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Article
Regeneration of Aluminum Matrix Composite Reinforced by SiCp and GCsf Using Gas Tungsten Arc Welding Technology
Materials 2021, 14(21), 6410; https://doi.org/10.3390/ma14216410 - 26 Oct 2021
Viewed by 347
Abstract
The main motivation behind the presented research was the regeneration of the damaged surface of composite materials. The testing of melting and pad welding of the composite surface by Gas Tungsten Arc Welding (GTAW) with alternating current (AC) were carried out. The material [...] Read more.
The main motivation behind the presented research was the regeneration of the damaged surface of composite materials. The testing of melting and pad welding of the composite surface by Gas Tungsten Arc Welding (GTAW) with alternating current (AC) were carried out. The material of investigation was an AlSi12/SiCp + GCsf hybrid composite made by a centrifugal casting process. The composite was reinforced with 5 wt.% of silicon carbide particles and 5 wt.% of glassy carbon spheres. The composites were investigated in tribological tests. It was found that there was a possibility for modification or regeneration of the surface with pad welding technology. Recommended for the repairs was the pad welding method with filler metal with a chemical composition similar to the aluminum matrix composite (ISO 18273 S Al4047A (AlSi12 [A])). The surface of the pad welding was characterized by the correct structure with visible SiCp. No gases or pores were observed in the pad welding; this was due to a better homogeneity of the silicon carbide (SiCp) distribution in the composite and better filling spaces between liquid metal particles in comparison to the base material. Based on the tribological tests, it was found that the lowest wear was observed for the composite surface after pad welding. This was related to the small number of reinforcing particles and their agreeable bonding with the matrix. The plastic deformation of the Al matrix and scratching by worn particles were a dominant wear mechanism of the surface. Full article
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Article
Matrix Composite Coatings Deposited on AISI 4715 Steel by Powder Plasma-Transferred Arc Welding. Part 3. Comparison of the Brittle Fracture Resistance of Wear-Resistant Composite Layers Surfaced Using the PPTAW Method
Materials 2021, 14(20), 6066; https://doi.org/10.3390/ma14206066 - 14 Oct 2021
Viewed by 370
Abstract
This article is the last of a series of publications included in the MDPI special edition entitled “Innovative Technologies and Materials for the Production of Mechanical, Thermal and Corrosion Wear-Resistant Surface Layers and Coatings”. Powder plasma-transferred arc welding (PPTAW) was used to [...] Read more.
This article is the last of a series of publications included in the MDPI special edition entitled “Innovative Technologies and Materials for the Production of Mechanical, Thermal and Corrosion Wear-Resistant Surface Layers and Coatings”. Powder plasma-transferred arc welding (PPTAW) was used to surface metal matrix composite (MMC) layers using a mixture of cobalt (Co3) and nickel (Ni3) alloy powders. These powders contained different proportions and types of hard reinforcing phases in the form of ceramic carbides (TiC and WC-W2C), titanium diboride (TiB2), and of tungsten-coated synthetic polycrystalline diamond (PD-W). The resistance of the composite layers to cracking under the influence of dynamic loading was determined using Charpy hammer impact tests. The results showed that the various interactions between the ceramic particles and the metal matrix significantly affected the formation process and porosity of the composite surfacing welds on the AISI 4715 low-alloy structural steel substrate. They also affected the distribution and proportion of reinforcing-phase particles in the matrix. The size, shape, and type of the ceramic reinforcement particles and the surfacing weld density significantly impacted the brittleness of the padded MMC layer. The fracture toughness increased upon decreasing the particle size of the hard reinforcing phase in the nickel alloy matrix and upon increasing the composite density. The calculated mean critical stress intensity factor KIc of the steel samples with deposited layers of cobalt alloy reinforced with TiC and PD-W particles was 4.3 MPa⋅m12 higher than that of the nickel alloy reinforced with TiC and WC-W2C particles. Full article
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Article
Hybrid Welding (Laser–Electric Arc MAG) of High Yield Point Steel S960QL
Materials 2021, 14(18), 5447; https://doi.org/10.3390/ma14185447 - 20 Sep 2021
Viewed by 638
Abstract
The article discusses the effect of the hybrid-welding process (laser–electric arc MAG Metal Active Gas) on the structure and properties of butt joints (having various thicknesses, i.e., 5 mm and 7 mm) made of steel S960QL. Welding tests were performed in the [...] Read more.
The article discusses the effect of the hybrid-welding process (laser–electric arc MAG Metal Active Gas) on the structure and properties of butt joints (having various thicknesses, i.e., 5 mm and 7 mm) made of steel S960QL. Welding tests were performed in the flat position (PA) and in the horizontal position (PC). Joints made of steel S960QL in the above-presented configuration are present in elements of crane structures (e.g., telescopic crane jibs). The welding tests involved the use of the G Mn4Ni1.5CrMo solid electrode wire and the Ar+18% CO2 shielding gas mixture (M21) (used in the MAG method). Non-destructive visual and radiographic tests did not reveal the presence of any welding imperfections in the joints. The welded joints obtained in the tests represented quality level B in accordance with the requirements of the ISO 12932 standard. Microscopic metallographic tests revealed that the heat-affected zone (HAZ) contained the coarse-grained martensitic structure resulting from the effect of the complex welding thermal cycle on the microstructure of the joints. Destructive tests revealed that the joints were characterised by tensile strength similar to that of the base material. The hybrid welding (laser–MAG) of steel S960QL enabled the obtainment of joints characterised by favourable plastic properties and impact energy exceeding 27 J. The tests revealed the possibility of making hybrid-welded joints satisfying the quality-related requirements specified in the ISO 15614-14 standard. Full article
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Article
Influence of Co Content and Chemical Nature of the Co Binder on the Corrosion Resistance of Nanostructured WC-Co Hardmetals in Acidic Solution
Materials 2021, 14(14), 3933; https://doi.org/10.3390/ma14143933 - 14 Jul 2021
Viewed by 562
Abstract
The electrochemical corrosion resistance of nanostructured hardmetals with grain sizes dWC < 200 nm was researched concerning Co content and the chemical nature of the Co binder. Fully dense nanostructured hardmetals with the addition of grain growth inhibitors GGIs, VC and Cr [...] Read more.
The electrochemical corrosion resistance of nanostructured hardmetals with grain sizes dWC < 200 nm was researched concerning Co content and the chemical nature of the Co binder. Fully dense nanostructured hardmetals with the addition of grain growth inhibitors GGIs, VC and Cr3C2, and 5 wt.%Co, 10 wt.%Co, and 15 wt.%Co were developed by a one cycle sinter-HIP process. The samples were detailly characterized in terms of microstructural characteristics and researched in the solution of H2SO4 + CO2 by direct and alternative current techniques, including electrochemical impedance spectroscopy. Performed analysis revealed a homogeneous microstructure of equal and uniform grain size for different Co contents. The importance of GGIs content adjustment was established as a key factor of obtaining a homogeneous microstructure with WC grain size retained at the same values as in starting mixtures of different Co binder content. From the conducted research, Co content has shown to be the dominant influential factor governing electrochemical corrosion resistance of nanostructured hardmetals compared to the chemical composition of the Co binder and WC grain size. Negative values of Ecorr measured for 30 min in 96% H2SO4 + CO2 were obtained for all samples indicating material dissolution and instability in acidic solution. Higher values of Rp and lower values of icorr and vcorr were obtained for samples with lower Co content. In contrast, the anodic Tafel slope increases with increasing Co content which could be attributed to more pronounced oxidation of the higher Co content samples. Previously researched samples with the same composition but different chemical composition of the binder were introduced in the analysis. The chemical composition of the Co binder showed an influence; samples with lower relative magnetic saturation related to lower C content added to the starting mixtures and more W dissolved in the Co binder during the sintering process showed better corrosion resistance. WC-5Co sample with significantly lower magnetic saturation value showed approximately 30% lower corrosion rate. WC-10Co sample with slightly lower relative magnetic saturation value and showed approximately 10% lower corrosion rate. Higher content of Cr3C2 dissolved in the binder contributed to a lower corrosion rate. Slight VC increase did not contribute to corrosion resistance. Superior corrosion resistance is attributed to W and C dissolved in the Co binder, lower magnetic saturation, or WC grain size of the sintered sample. Full article
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Article
Microstructure and Abrasive Wear Resistance of Metal Matrix Composite Coatings Deposited on Steel Grade AISI 4715 by Powder Plasma Transferred Arc Welding Part 2. Mechanical and Structural Properties of a Nickel-Based Alloy Surface Layer Reinforced with Particles of Tungsten Carbide and Synthetic Metal–Diamond Composite
Materials 2021, 14(11), 2805; https://doi.org/10.3390/ma14112805 - 25 May 2021
Cited by 2 | Viewed by 563
Abstract
The article is the continuation of a cycle of works published in a Special Issue of MDPI entitled “Innovative Technologies and Materials for the Production of Mechanical, Thermal and Corrosion Wear-Resistant Surface Layers and Coatings” related to tests concerning the microstructure and mechanical [...] Read more.
The article is the continuation of a cycle of works published in a Special Issue of MDPI entitled “Innovative Technologies and Materials for the Production of Mechanical, Thermal and Corrosion Wear-Resistant Surface Layers and Coatings” related to tests concerning the microstructure and mechanical properties of innovative surface layers made using the Powder Plasma Transferred Arc Welding (PPTAW) method and intended for work surfaces of drilling tools and machinery applied in the extraction industry. A layer subjected to tests was a metal matrix composite, made using powder based on a nickel alloy containing spherical fused tungsten carbide (SFTC) particles, which are fused tungsten carbide (FTC) particles and spherical particles of tungsten-coated synthetic metal–diamond composite (PD-W). The layer was deposited on the substrate of low-alloy structural steel grade AISI 4715. The results showed that the chemical composition of the metallic powder as well as the content of the hard phase constituting the matrix enabled the making of a powder filler material characterised by very good weldability and appropriate melting. It was also found that the structure of the Ni-WC-PD-W layer was complex and that proper claddings (characterised by the uniform distribution of tungsten carbide (WC)) were formed in relation to specific cladding process parameters. In addition, the structure of the composite layer revealed the partial thermal and structural decomposition of tungsten carbide, while the particles of the synthetic metal–diamond composite remained coherent. The deposited surface layer was characterised by favourable resistance to moderate dynamic impact loads with a potential energy of 200 J, yet at the same time, by over 12 times lower metal–mineral abrasive wear resistance than the previously tested surface layer made of cobalt-based composite powder, the matrix of which contained the hard phase composed of TiC particles and synthetic metal–diamond composite. The lower abrasive wear resistance could result from a different mechanism responsible for the hardening of the spherical particles of the hard phase susceptible to separation from the metal matrix, as well as from a different mechanism of tribological wear. Full article
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Article
Microstructure and Abrasive Wear Resistance of Metal Matrix Composite Coatings Deposited on Steel Grade AISI 4715 by Powder Plasma Transferred Arc Welding Part 1. Mechanical and Structural Properties of a Cobalt-Based Alloy Surface Layer Reinforced with Particles of Titanium Carbide and Synthetic Metal–Diamond Composite
Materials 2021, 14(9), 2382; https://doi.org/10.3390/ma14092382 - 03 May 2021
Cited by 2 | Viewed by 720
Abstract
The article discusses test results concerning an innovative surface layer obtained using the cladding with powder plasma transferred arc welding (PPTAW) method. The above-named layer, being a metal matrix composite (MCM), is characterised by high abrasive wear resistance, resistance to pressure and impact [...] Read more.
The article discusses test results concerning an innovative surface layer obtained using the cladding with powder plasma transferred arc welding (PPTAW) method. The above-named layer, being a metal matrix composite (MCM), is characterised by high abrasive wear resistance, resistance to pressure and impact loads, and the possibility of operation at elevated temperatures. The layer was made using powder in the form of a cobalt alloy-based composite reinforced with monocarbide TiC particles and superhard spherical particles of synthetic metal–diamond composite provided with tungsten coating. The surface layer was deposited on a sheet made of low-alloy structural steel grade AISI 4715. The layer is intended for surfaces of inserts of drilling tools used in the extraction industry. The results showed the lack of the thermal and structural decomposition of the hard layer reinforcing the matrix during the cladding process, its very high resistance to metal-mineral abrasive wear and its resistance to moderate impact loads. The abrasive wear resistance of the deposited layer with particles of TiC and synthetic metal–diamond composite was about than 140 times higher than the abrasive wear resistance of abrasion resistant heat-treated steel having a nominal hardness of 400 HBW. The use of diamond as a metal matrix reinforcement in order to increase the abrasive resistance of the PPTAW overlay layer is a new and innovative area of inquiry. There is no information related to tests concerning metal matrix surface layers reinforced with synthetic metal–diamond composite and obtained using PPTAW method. Full article
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Article
Characterization of the Structure, Mechanical Properties and Erosive Resistance of the Laser Cladded Inconel 625-Based Coatings Reinforced by TiC Particles
Materials 2021, 14(9), 2225; https://doi.org/10.3390/ma14092225 - 26 Apr 2021
Cited by 1 | Viewed by 624
Abstract
The article presents research in the field of laser cladding of metal-matrix composite (MMC) coatings. Nickel-based superalloys show attractive properties including high tensile strength, fatigue resistance, high-temperature corrosion resistance and toughness, which makes them widely used in the industry. Due to the insufficient [...] Read more.
The article presents research in the field of laser cladding of metal-matrix composite (MMC) coatings. Nickel-based superalloys show attractive properties including high tensile strength, fatigue resistance, high-temperature corrosion resistance and toughness, which makes them widely used in the industry. Due to the insufficient wear resistance of nickel-based superalloys, many scientists are investigating the possibility of producing nickel-based superalloys matrix composites. For this study, the powder mixtures of Inconel 625 superalloy with 10, 20 and 40 vol.% of TiC particles were used to produce MMC coatings by laser cladding. The titanium carbides were chosen as reinforcing material due to high thermal stability and hardness. The multi-run coatings were tested using penetrant testing, macroscopic and microscopic observations, microhardness measurements and solid particle erosive test according to ASTM G76-04 standard. The TiC particles partially dissolved in the structure during the laser cladding process, which resulted in titanium and carbon enrichment of the matrix and the occurrence of precipitates formation in the structure. The process parameters and coatings chemical composition variation had an influence on coatings average hardness and erosion rates. Full article
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Review

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Review
Comparison of the Values of Solar Cell Contact Resistivity Measured with the Transmission Line Method (TLM) and the Potential Difference (PD)
Materials 2021, 14(19), 5590; https://doi.org/10.3390/ma14195590 - 26 Sep 2021
Viewed by 377
Abstract
This work presents a comparison of values of the contact resistivity of silicon solar cells obtained using the following methods: the transmission line model method (TLM) and the potential difference method (PD). Investigations were performed with two independent scientific units. The samples were [...] Read more.
This work presents a comparison of values of the contact resistivity of silicon solar cells obtained using the following methods: the transmission line model method (TLM) and the potential difference method (PD). Investigations were performed with two independent scientific units. The samples were manufactured with silver front electrodes. The co-firing process was performed in an infrared belt furnace in a temperature range of 840 to 960 °C. The electrical properties of a batch of solar cells fabricated in two cycles were investigated. This work focuses on the different metallisation temperatures of co-firing solar cells and measurements were carried out using the methods mentioned. In the TLM and PD methods, the same calculation formulae were used. Moreover, solar cell parameters measured with these methods had the same, similar, or sometimes different but strongly correlated values. Based on an analysis of the selected databases, this article diagnoses the recent and current state of knowledge regarding the employment of the TLM and PD methods and the available hardware base. These methods are of interest to various research centres, groups of specialists dealing with the optimisation of the electrical properties of silicon photovoltaic cells, and designers of measuring instruments. Full article
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