Abstract:Slurry aluminide coatings were produced on Ti-based alloy Ti6Al4V in an argon atmosphere. A slurry with a newly-developed composition was applied, consisting of: powders of aluminium and silicon, a fused mixture of salts as an activator and a water solution of a soluble glass as an inorganic binder. The coating production parameters were varied: annealing temperatures of 900, 1000 and 1100°C were used for annealing times of 2, 4 and 6 h. The microstructure, chemical composition and phase composition of the coa… Show more
“…The usefulness of this method for the production of both silicide and silicide-aluminide coatings on molybdenum alloy has been confirmed in previous works [21][22][23][24]. This slurry method can be applicable for materials of a raw cast surface thanks to the presence of a flux in the slurry [21].…”
Section: Introductionsupporting
confidence: 58%
“…This slurry method can be applicable for materials of a raw cast surface thanks to the presence of a flux in the slurry [21]. It is possible to produce aluminide coatings on titanium and nickel alloys [23,24]. It is also possible to produce a silicide coating on molybdenum alloy composed of three sub-layers with a phase composition according to the Mo-Si diagram system [22].…”
New slurry cementation method was used to produce silicide and silicide-aluminide protective coatings on molybdenum alloy (TZM). The slurry cementation processes were carried out at a temperature of 1000 °C in different time intervals with the use of varied slurry mass values. The microstructure and thickness of the coatings were studied by means of scanning microscopy. Chemical composition using X-ray microanalysis and phase composition using X-ray diffraction were also investigated. Coating microhardness was determined. The obtained coatings had a multilayer structure. Phases from the Al-Si-Mo system were observed in silicide-aluminide coatings and phases from the Si-Mo system were observed in silicide coatings. The microhardness strongly depended on the phase composition of the coating. It was demonstrated that slurry mass values had an important influence on the morphology and growth kinetics of silicide-aluminide coatings. In the case of a small amount of the slurry, the deficiency of alloying elements occurring during long processes reduces growth kinetics and can lead to void formation in the structure of silicide-aluminide coatings.
“…The usefulness of this method for the production of both silicide and silicide-aluminide coatings on molybdenum alloy has been confirmed in previous works [21][22][23][24]. This slurry method can be applicable for materials of a raw cast surface thanks to the presence of a flux in the slurry [21].…”
Section: Introductionsupporting
confidence: 58%
“…This slurry method can be applicable for materials of a raw cast surface thanks to the presence of a flux in the slurry [21]. It is possible to produce aluminide coatings on titanium and nickel alloys [23,24]. It is also possible to produce a silicide coating on molybdenum alloy composed of three sub-layers with a phase composition according to the Mo-Si diagram system [22].…”
New slurry cementation method was used to produce silicide and silicide-aluminide protective coatings on molybdenum alloy (TZM). The slurry cementation processes were carried out at a temperature of 1000 °C in different time intervals with the use of varied slurry mass values. The microstructure and thickness of the coatings were studied by means of scanning microscopy. Chemical composition using X-ray microanalysis and phase composition using X-ray diffraction were also investigated. Coating microhardness was determined. The obtained coatings had a multilayer structure. Phases from the Al-Si-Mo system were observed in silicide-aluminide coatings and phases from the Si-Mo system were observed in silicide coatings. The microhardness strongly depended on the phase composition of the coating. It was demonstrated that slurry mass values had an important influence on the morphology and growth kinetics of silicide-aluminide coatings. In the case of a small amount of the slurry, the deficiency of alloying elements occurring during long processes reduces growth kinetics and can lead to void formation in the structure of silicide-aluminide coatings.
“…In general, the main differences in the structure of coatings are illustrated in Figure 2. A comprehensive elucidation of the coating structure has been provided in a previous publication [21].…”
Section: Resultsmentioning
confidence: 99%
“…In general, the main differences in the structure of coatings are illustrated in Figure 2. A comprehensive elucidation of the coating structure has been provided in a previous publication [21]. Figure 2 Microstructures of Al-Si coating on Ti-6Al-4V manufacturing in argon atmosphere, the sample number (a) 2 (1000 °C/2 h), (b) 8 (1100 °C/6 h).…”
A proprietary slurry cementation method was used to produce silicide-aluminide coatings on alloy Ti-6Al-4V. The cementation processes were carried out at 900-1100 °C for 2-6 h. The coatings exhibited a stratified configuration characterised by a phase arrangement that demonstrates favourable attributes pertaining to mechanical and corrosion resistance capabilities, namely, the presence of aluminium-enriched phases at the coating surface and titanium-enriched phases proximity to the substrate. The cyclic oxidation behaviour at 800 °C for 30 twenty-two-hour cycles was investigated. The characterisation of the structure of coatings was carried out through the use of scanning microscopy, X-ray microanalysis, and Xray diffraction techniques. The coatings have excellent resistance to cyclic oxidation, resulting from the gradient structure and the establishment of a protective alumina layer on the surface. The coatings were characterised by good resistance to thermal shocks. The microcracks formed during thermal shocks were filled with an alumina, which renders the coatings self-healing.
“…Silicon addition was found as an effective way to improve the oxidation resistance of aluminide coatings. Low oxygen pressure fusing [10], powder pack cementation [12], hot dipping [13], slurry method [14], and hot stamping [15] methods were studied to form Al-Si coatings on different substrate materials to improve oxidation resistance. The formation of an additional oxide phase (SiO 2 ) further benefits the protection of the nickel-based superalloy substrate, by delaying the formation of harmful phases (NiO and γ -Ni 3 Al) [16].…”
Inconel superalloys are used substantially in high-temperature environments. However, these alloys suffer from corrosion and wear. Attempts to overcome these drawbacks involve coating the metal with different techniques and materials. In this study, a new method with increasing potential was utilized. Using the mechanical alloying process in a planetary ball mill vial, alloying and the Al-Si coatings were concurrently achieved on Inconel 625 substrates. Different process control agent (PCA) ratios, milling ball diameters, and milling times were used to improve coating properties. Macro and microstructure, morphology, microhardness, and roughness values of samples were evaluated and compared. Additionally, crystallographic and cross-sectional properties were investigated in order to optimize the processing conditions. The results indicated that increasing the diameter of the grinding ball enhanced the hardness and thickness of these coatings and increased the roughness values. Longer processing time also enhanced the thickness with mechanical values. However, under these conditions, coating homogeneity decreased, and incompatible regions were formed on the coatings. PCA content brought a refined grain structure, hence showed better mechanical properties. On the other hand, processing time should be increased to get a denser and thicker protective layer against the operational conditions.
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