Glass-ceramic Coatings Research Articles

The evolution mechanism of ethylene-based and glass-ceramic as composited anti-seepage masking layer for Ni-based superalloy during aluminizing

This study addresses the diverse application requirements of turbine blades by utilizing a composite anti-seepage masking layer to protect the Ni-based superalloy from Al deposition during aluminizing. Simultaneously, the unmasked areas simulate blade airfoils for aluminized coating formation. Ethylene-based and glass-ceramic coatings were evaluated for anti-seepage effectiveness after aluminizing at 800 ∼ 1000 ℃. The results reveal that ethylene-based coatings prevent Al diffusion into the substrate at 800 ℃, and degradation occurs at higher temperatures. However, adding a glass-ceramic coating significantly enhances high-temperature stability and suppresses ethylene-based coating fluidity. The composited anti-seepage masking layer, with the ethylene-based and glass-ceramic coating applied twice, exhibits excellent anti-seepage masking performance on GH4169, DZ22B, and K477 superalloys, providing protection and easy removal without affecting unmasked areas. This approach improves the comprehensive performance of turbine blades, meeting the requirements of both dovetail and airfoil sections.

Protection of 316L Steel Against LBE Corrosion by a CaO-MgO-Al2O3-SiO2 Glass–Ceramic Coating

A CaO-MgO-Al2O3-SiO2 glass–ceramic coating was prepared by the slurry method and subsequent sintering to improve the corrosion resistance of 316L steel in liquid lead–bismuth eutectic alloy at high temperatures. The glass–ceramic coating, sintered at 884 °C, was dense and demonstrated strong adhesion to the substrate. It was composed of the crystalline phases diopside (CaMgSi2O6) and anorthite (CaAl2Si2O8) and had an average Vickers hardness of 595 HV, which was over three times that of 316L steel. After corrosion in an oxygen-saturated, static lead–bismuth eutectic alloy at 500 °C for 1000 h, the uncoated 316L experienced significant mass gain (0.04 g) due to severe oxidative corrosion, resulting in the formation of Fe3O4 and Pb2O on its surface. In contrast, the glass–ceramic-coated specimens showed a very small mass gain (0.0012 g) after corrosion. The coating maintained good thermal stability; its crystalline phase composition remained largely unchanged after the corrosion test. The glass–ceramic coating still exhibited dense microstructure and tightly adhered to the substrate after corrosion. There was no evident penetration of lead–bismuth into the coating, and no dissolution of the coating’s elements into the lead–bismuth alloy was detected. These observations confirm that the glass–ceramic coating possessed superior corrosion resistance in liquid lead–bismuth eutectic environments.

Enhanced thermal shock resistance of SiCf/SiC composites with Y-Al-Si-O glass ceramic environmental barrier coatings in water-oxygen conditions at 1350°C

In this study, Y-Al-Si-O(YAS) glass-ceramic environmental barrier coatings were prepared after modifying CVI-SiCf/SiC composites with microcrystalline glass. The resistance of both SiCf/SiC and SiCf/SiC with YAS-EBC to thermal shock was systematically examined using a water quenching method. The findings demonstrate that the SiCf/SiC composites with YAS-EBC exhibits outstanding thermal shock resistance. The coefficient of thermal expansion (CTE) of the YAS coating exhibits minimal deviation from that of SiCf/SiC and possesses a low modulus of elasticity. Upon experiencing thermal shock, the YAS coating is subjected to tensile stress, with an average thermal stress of merely ∼4.4 MPa. After undergoing 100 cycles, there was no evidence of debonding between the coating and the substrate, nor was a thermally grown oxide (TGO) layer observed at the interface. This research provides a credible method and theoretical foundation for enhancing the thermal shock resistance behavior of CVI-SiCf/SiC composites.

Influence of Al2O3 content on microstructure and oxidation resistance of glass-ceramic coatings for 06Ni9DR alloy steel

Glass-ceramic coatings with different Al2O3 content were prepared for oxidation protection of 06Ni9DR alloy steel. The microstructure and oxidation protection rate of coatings with different content of Al2O3 at 1200 °C were investigated. The results showed that the average internal pore size decreased with Al2O3 content and the protection of the coating increased after oxidation test for 3 h. The oxidation protection rate of coating with 20 wt% Al2O3 was the worst due to many large-size pores in the coating and bad thermal stability, and the melting of FeO into the liquid phase accelerated the formation of cracks inside the steel and further deteriorate the oxidation protection. As the alumina content increased, the liquid phase in the coating significantly decreased, and correspondingly the thermal stability increased; At the same time, a large number of 0.5–3 μm pores were formed in the coating, which effectively prolonged the oxygen diffusion path, further enhanced the oxidation resistance of the coating. The glass-ceramic coating with 80 wt% Al2O3 exhibited good oxidation protection, reaching 73.6 ± 1.6 % at 1200 °C for 3 h.

Polymer-derived coatings with La2Zr2O7 and glass fillers: Preparation and characterisation

This study investigated the impact of La2Zr2O7 (LZ) and different types of glass on the performance of polymer-derived ceramic (PDC) coatings on AISI 441 stainless steel substrates. Four double-layer PDC-based glass-ceramic coatings containing LZ and different glass fillers were prepared by dip coating. The LZ powder was synthesised by solid-state reaction (SSR): powder morphology, crystal structure, and thermal stability were analysed. X-ray diffraction (XRD) detected a LZ pyrochlore phase after annealing at 1300 and 1400 °C with a trace of t-ZrO2. Four different glass compositions, namely BaO-Al2O3-SiO2 (BAS), BaO-Al2O3-La2O3-B2O3-SiO2 (BALBS), CaO-B2O3-SiO2 (CBS), and BaO-ZnO-MgO-B2O3-SiO2 (BZMBS), were also synthesised as fillers for PDC coatings. The glass transition and crystallisation temperatures of the glasses were determined using differential scanning calorimetry (DSC). The coating systems, consisting of a Durazane 2250 bond coat and a top coat (Durazane 1800 + LZ filler + different glass sealants), were prepared. After pyrolysis of the coatings at 900 °C, some of the glasses partially crystallised. Scanning electron microscopy (SEM) revealed that the layers containing BAS, BALBS and CBS glass were dense, with good adhesion to the substrate, and with occasional presence of larger pores and cracks. Delamination of the upper layer was observed in the coating with the BZMBS glass filler.

Investigation of acid exposure duration on migration behavior of sodium borosilicate glass-ceramic coatings

This study investigates the migration behavior of Na2O-B2O3-SiO2 glass-ceramic coatings under different exposure durations. Sinter-crystallization at 830 °C for 4.5 min transforms the glass into a crystalline phase. Coatings were immersed in 3% acetic acid solutions for durations ranging from 15 to 960 min. Chemical migration was measured using ICP-MS analysis, while SEM and surface profilometry assessed surface morphology and roughness. Coatings remained compliant with ISO 4531:2022 food-contact standard, even after 960 min. Dissolution of alkaline network modifiers initially increased roughness, which then returned to the initial value. This research provides insights into the stability and applicability of glass-ceramic coatings for long-term use in food-contact surfaces, contributing to the field of surface coatings and food safety.

High-temperature aqueous corrosion of MO–Na2O–B2O3–SiO2 glass and glass-ceramic coatings on metallic substrates: Effect of alkaline earth metals M2+= {Ca2+, Sr2+, Ba2+}

This investigation aims to assess the impact of 2 A alkaline-earth oxides on the alteration of glass/glass-ceramic coatings on steel under conditions of exposure to hot water. Experiments involved integrating CaO, SrO, and BaO into sodium-borosilicate glass systems after that a melting-quenching process to obtain frits. Coated and sinter-crystallized samples denoted as GC-Ca, GC-Sr, and GCC-Ba were exposed to hot aqueous corrosion according to DIN 4753–3 at 95 °C, which determined weight loss after 42 days. ICP-MS analyzed aqueous solutions for element leaching. Results indicated that glass-ceramic coatings (GCC-Ba) outperformed glass coating(GC-Ca, GC-Sr). GCC-Ba demonstrated enhanced stability, attributed to limited ion exchange and diffusion at high temperatures, enhancing corrosion resistance, supported by sanbornite crystal phase presence. Total element release by ICP-MS and 42 days of hot water corrosion coatings' weight loss after 42-day corrosion test lined up: GC-Sr > GC-Ca > GCC-Ba.

Influence of nano-CuO modification on crystallization behavior and surface characteristics of P2O5 containing Li2O-ZnO-B2O3-SiO2 glass-ceramics

This paper investigates the impact of nano-CuO addition on the crystallization process and surface properties of phosphate containing lithium zinc borosilicate glass-ceramic coatings. A comprehensive analysis was performed using diverse thermal, structural, and morphological techniques such as hot stage microscope, differential thermal analysis, X-ray diffraction analysis and scanning electron microscopy. Thermal analysis revealed a glass transition temperature of 478.5 °C and a crystallization onset temperature of 595.6 °C. The coefficient of thermal expansion was measured to be 8.94 × 10−6.°C−1. Viscosity measurements indicated a significant decrease in viscosity with increasing temperature, following the Vogel-Fulcher-Tammann equation. Kinetic studies revealed an activation energy of 11.36 kJ/mol for the crystallization process, suggesting potential kinetic hindrance for the reference glass-ceramic coating. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses confirmed the formation of a crystalline phases of Li2ZnSiO4 and Li3PO4 at crystallization temperatures above 750 °C. Nano-CuO addition was found to promote crystal formation and increase the inter-crystal spacing according to the SEM analysis. Optical microscopy and 3D surface analysis revealed that nano-CuO addition refined surface texture and reduced the surface roughness of the glass-ceramic coatings at varying crystallization temperatures of 750, 800 and 850 °C. Moreover, contact angle measurements indicated that nano-CuO addition decreased the wetting angle of the coatings around 62 %, suggesting improved hydrophilicity. The findings suggest that nano-CuO addition can enhance the crystallization kinetics and improve the surface quality and hydrophilicity of glass-ceramic coatings.

Exploring luminescence in transparent Glass–Ceramic coating: Study on Pr3+/ Dy3+ Co-doped SrO–Al2O3–SiO2 Glass–Ceramic particles

This study aimed to fabricate transparent glass–ceramic coatings with luminescent characteristics. To this end, a SrO–Al2O3–SiO2 glass–ceramic system doped with Pr3+ and Dy3+ ions, referred to as luminescent glass–ceramic (LGC), was synthesized via melting at 1550 °C for 1 h. LGCs were added as mill additives to the transparent glass–ceramic coating recipe at increasing weight percentages of 5, 10, 20, and 40% (5Pr, 10Pr, 20Pr, and 40Pr, respectively). The coating specimens fabricated through the wet spraying technique were vitrified and recrystallized at 820 °C for 4 min, resulting in an LGC coating. Further, the chemical composition, phase structure, thermal behavior, and bonding characteristics of the LGC systems were analyzed, and spectrofluorometer and scanning electron microscope (SEM) analyses were performed after the coating procedure. The SEM indicated an increase in particle intensity per unit surface area. The spectrofluorometric analysis revealed that the standard sample did not display any discernible peaks; however, samples supplemented with particles exhibit emission bands at wavelengths of 485 (4F9/2 → 6H15/2, blue) and 575 nm (4F9/2 → 6H13/2, yellow) for Dy3+ ions and at 485 nm (3P0→3H4, blue) for Pr3+ ions. According to the CIE color graph, an increase in the quantity of added particles resulted in the region shifting toward the green–white area from the center of the blue–green region in the standard sample.

Antifouling performance of TiO2-based SiO2–Na2O–K2O glass-ceramic coatings in marine environments

Biofouling refers to the accumulation of organisms on artificial surfaces. This phenomenon poses significant challenges in industrial processes, including reduced energy efficiency and increased fuel consumption. Antifouling coating systems are designed to prevent biofouling on artificial surfaces. Currently, there is a growing focus on developing eco-friendly solutions to mitigate the environmental impact of these antifouling coatings. In this study, the antifouling (AF) performance of a TiO2-based borosilicate glass-ceramic coating (Ti-GCC) system was evaluated in terms of barnacle settlement on the coating surface. To create anatase crystals in a coating, a special precursor glass (Ti-PG) formulation, Na2O–K2O–TiO2–B2O3–Al2O3–SiO2–P2O5–F, with <10 % of Na2O and 20 % TiO2 along with other components was used. The Ti-PG was characterised through X-ray fluorescence (XRF) spectroscopy to determine the chemical composition. The milled Ti-PG with additives was applied on a steel substrate using a spray gun and devitrified at 550 °C and 860 °C for 6 min. The phase determination, surface evaluation, thermal behaviour analysis, and AF evaluation of the Ti-GCC were conducted through X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), non-contact optical profilometry (NCOP), and thermogravimetric-differential thermal analysis (TG-DTA). The anatase crystal was determined to exist in the Ti-GCC structure. Although the AF evaluation results revealed that the Ti-GCC system had barnacle settlement (73.9 barnacles/cm2), the surface could be easily cleaned. Additionally, the EDS results confirmed that no biofilm was formed on the Ti-GCC's surface. The roughness of the surface before the AF evaluation and after the cleaning procedure was measured using NCOP, and the difference in surface roughness was examined. The small difference in the roughness of the surfaces suggested that the Ti-GCC system exhibited resistance to microbially induced corrosion (MIC). Furthermore, EDS mapping did not provide any evidence of barnacle diffusion into the coated layer. Furthermore, the thickness measurements of the cross-sectional area of the Ti-GCC before and after AF evaluation through SEM proved that coating depletion did not occur.

Thermal shock behavior and high-temperature oxidation performance of PDC-based environmental barrier coatings on AISI 441 stainless steel

The present work aimed to investigate the influence of different testing conditions on high-temperature oxidation performance of selected polymer-derived ceramic (PDC) environmental barrier coatings on AISI 441 stainless steel substrates. For this purpose, two types of double-layer PDC-based glass-ceramic coatings containing passive and glass fillers were fabricated using a combination of dip coating and spray coating processes. To evaluate the performance of the coatings in harsh environments simulating real applications, thermal cyclic tests in dry air, long-term static oxidation tests in humidified air, and thermal shock tests were performed. YAG, monoclinic ZrO2, cubic ZrO2, and a newly formed BaAl2Si2O8 phase were identified from XRD patterns of the tested PDC coatings. The SiO2 reflections, detected in the coatings after pyrolysis, were absent after both oxidation and thermal shock resistance tests. The SEM examination indicated that the performance of the studied PDC coatings was mainly affected by the microstructural modifications induced by differential sintering of the glass filler particles, leading to an expansion of existing pores, which represented preferential failure sites in the coating. In contrast, the existence of internal porosity relieved the residual stresses and reduced the driving force for crack extension, resulting in an increased thermal shock resistance. A combined scratch test based on the acoustic emission signal record along with the SEM observation of the resulting scratch tracks were also carried out. The most significant damage event in both tested PDC coatings was partial decohesion and surface chipping, which, however, did not translate into a critical adhesive failure. These findings confirm that the developed PDC coatings can be used for the protection of stainless steel in oxidizing environments up to 900 °C.

Antibacterial Matte Glass-Ceramic Coatings with Satin Texture for Ceramic Tiles

Antibacterial satin glass-ceramic coatings for ceramic tiles have been developed by one-stage firing on the basis of high-calcium zinc aluminum silicate frits, which are modified with heavy metal cations. The antibacterial effect of the developed matte glass-ceramic coatings with a satin texture was established due to the effect of potentiating the antibacterial activity of the combined action of the hardystonite crystalline phase and fillers of zinc and tin oxides.

Processing, Characterization, and Oxidation Resistance of Glass-Ceramic Coating on CoSb3

Power generation based on thermoelectric (TE) materials is very attractive due to its low environmental impact and waste heat recovery. Thermoelectric materials based on cobalt triantimonide CoSb3 exhibit one of the highest energy conversion efficiencies, revealing thermoelectric figures of merit, ZTs &gt; 1, but undergo oxidation above 380 °C and sublimation above 500 °C. In this work, a glass-ceramic coating was chosen to match the coefficient of thermal expansion (CTE) of the TE substrate 9.2 × 10−6 K−1 (200–400 °C), deposition temperature (max. 700 °C), and maximum working temperature (600 °C). Coating processing involved the production of glass powder and glass-ceramic sintering. The glass-ceramic and the coating/CoSb3 interface were systematically investigated by means of dilatometry, X-ray diffraction, and scanning and transmission electron microscopy. As a result, a coating with good substrate coverage and adherence was developed. Finally, oxidation tests were carried out at 500 and 600 °C in order to assess the protective properties of the glass-ceramic. Microstructural and chemical composition analysis indicated limited protective properties of the coating.

Glass-Ceramic Coating on Silver Electrode Surface via 3D Printing.

Silver electrodes are commonly used as a conductive layer for electromagnetic devices. It has the advantages of good conductivity, easy processing, and good bonding with a ceramic matrix. However, the low melting point (961 °C) results in a decrease in electrical conductivity and migration of silver ions under an electric field when it works at high temperatures. Using a dense coating layer on the silver surface is a feasible way to effectively prevent the performance fluctuation or failure of the electrodes without sacrificing its wave-transmitting performance. Calcium-magnesium-silicon glass-ceramic (CaMgSi2O6) is a diopside material that has been widely used in electronic packaging materials. However, CaMgSi2O6 glass-ceramics (CMS) are facing tough challenges, such as high sintering temperature and insufficient density after sintering, which significantly confine its applications. In this study, CaO, MgO, B2O3, and SiO2 were used as raw materials to manufacture a uniform glass coating on the silver and Al2O3 ceramics surface via 3D printing technology followed by high-temperature sintering. The dielectric and thermal properties of the glass/ceramic layer prepared with various CaO-MgO-B2O3-SiO2 components were studied, and the protective effect of the glass-ceramic coating on the silver substrate at high temperatures were evaluated. It was found that the viscosity of the paste and the surface density of the coating increase with the increase of solid contents. The 3D-printed coating shows well-bonded interfaces between the Ag layer, the CMS coating, and the Al2O3 substrate. The diffusion depth was 2.5 μm, and no obvious pores and cracks can be detected. According to the high density and well-bonded glass coating, the silver was well protected from the corrosion environment. Increasing the sintering temperature and extending the sintering time is beneficial to form the crystallinity and the densification effect. This study provides an effective method to manufacture a corrosive-resistant coating on an electrically conductive substrate with outstanding dielectric performances.

Novel Functional Glass-Ceramic Coatings on Titanium Substrates from Glass Powders and Reactive Silicone Binders.

‘Silica-defective glasses’, combined with a silicone binder, have been already shown as a promising solution for the manufacturing of glass–ceramics with complex geometries. A fundamental advantage is the fact that, after holding glass powders together from room temperature up to the firing temperature, the binder does not completely disappear. More precisely, it converts into silica when heat-treated in air. A specified ‘target’ glass–ceramic formulation results from the interaction between glass powders and the binder-derived silica. The present paper is dedicated to the extension of the approach to the coating of titanium substrates (to be used for dental and orthopedic applications), with a bioactive wollastonite–diopside glass–ceramic layer, by the simple airbrushing of suspensions of glass powders in alcoholic silicone solutions. The interaction between glass and silica from the decomposition of the binder led to crack-free glass–ceramic coatings, upon firing in air; in argon, the glass/silicone mixtures yielded novel composite coatings, embedding pyrolytic carbon. The latter phase enabled the absorption of infrared radiation from the coating, which is useful for disinfection purposes.

Fracture behavior of lightweight mullite-SiC refractories with porous aggregates coated with glass ceramic

Owing to the periodic mechanical stresses frequently suffered by refractories applied in cement rotary kilns, the study of fracture behavior is particularly significant for long life, safety, and reliable operation. In this work, bauxite aggregates and lightweight mullite aggregates with and without glass ceramic coatings were utilized in mullite-SiC refractories, and the fracture properties of the refractories were investigated and compared using the Brazilian test, digital image correlation technology, crack propagation path analysis, etc. The results show that the application of a glass ceramic coating on the surface of lightweight aggregates strengthens the interface between the porous mullite aggregates and the matrix, not only improving the compressive and tensile strength of the material but also increasing the number of crack branches and further improving fracture toughness. The compressive strength, tensile strength, and tensile displacement of refractories with 50 vol% coated lightweight aggregate increased by 53.1%, 67.6%, and 42.3%, respectively, compared to traditional mullite-SiC refractories.

Nanostructural glass composite coatings

The results of the study of glass-composite nanostructured self-lubricating coatings are presented. The developed glass composite is an antifriction material with an ultrafine structure. The structural components of these coatings significantly affect the graphitization process and provide an antifriction surface layer of α-graphite. The formation of this layer makes it possible to significantly minimize the contact parameters in the friction region.&#x0D; The developed antifriction nanostructured glass-ceramic self-lubricating coatings containing magnesium carbide and structural components that promote surface graphitization do not contain expensive and scarce components, meet environmental safety requirements, and have high performance characteristics. A significant effect of aluminoborosilicate in the form of a glass phase on the tribological properties of coatings is noted. An increase in adhesive strength is achieved by forming a surface layer of glassy sodium silicate. Using X-ray phase analysis, it was found that the intercalating elements in the subsurface zone-graphite system at the initial stage of the process were Mg2+, Al3+, Cu2+ ions, which randomly penetrated into the interlayer space of the graphite matrix. At sliding speeds of more than 3.0 m/s, intercalates of binary molecular compounds of these elements with oxygen were found in the layered system of graphite. Their intercalation is accompanied by a sequence of repetitive stages, which are reversible with a change in tribological parameters and are characterized by a specific transformation of the structure and, above all, by an increase in the distance between layers due to the influence of various types of interlayer defects and the introduction of intercalants.&#x0D; The presence of near-surface particles in the graphite layer does not affect the tribotechnical characteristics of the coatings. The developed glass-composite nanostructured self-lubricating coatings have high antifriction characteristics throughout the entire load-speed range

Abrasion-resistant CMAS glass-ceramic coatings incorporated with B4C particles

ABSTRACT One of the most significant mechanical characteristics of glass-ceramic coatings (GCCS) is abrasion resistance, which is particularly pertinent when contamination from the coated metallic surface is not desired. The influence of incorporating boron carbide (B4C) as a hard particle into the CaO–MgO–Al2O3–SiO2 GCC on the abrasion resistance was examined in this study. A PEI Abraser was used to evaluate the abrasion resistance over 5000 cycles, with mass loss recorded every 1000 cycles. Mass loss following the abrasion test was observed to decrease when the amount of added B4C was increased, indicating that the abrasion resistance was enhanced by B4C addition. The addition of 16 wt-% B4C has had the strongest interface among the matrix/B4C particles, resulting in higher abrasion resistance due to reduced crack formation and porosity, and yielded a decrease in mass loss of about 54%, colour change of <2 in terms of ΔE and gloss change about 40%.

Preparation and sealing effects of Mg–Al–Si–Ba–O-based glass-ceramic coatings on NTC thermistors

Herein, Mg–Al–Si–Ba–O-based glass ceramics were studied as potential candidates to protect Mn–Co–Ni–O-based negative temperature coefficient (NTC) thermistors at high temperatures such as 900 °C. The ceramics were prepared in three glass formulations (1#: 15MgO–15Al2O3-44.7SiO2–25BaO, 2#: 17MgO–17Al2O3–41SiO2–25BaO and 3#: 17MgO–17Al2O3–41SiO2–20BaO–5Y2O3 (in mol%)) and their glass-transition temperatures (Tg) were determined using the differential scanning calorimetry (DSC) method. Scanning electronic microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the parent glasses and glass-ceramic coatings. The sealing effects of the glass ceramics were examined by conducting an insulation test. The glass-ceramic sealing structures were subjected to 1000 thermal shock cycles at temperatures varying from room temperature to 900 °C. Notably, the sealing structure of glass-ceramic coating 1# was compact at a Tg of 760.9 °C. The glass-ceramic coatings effectively maintained the NTC properties of the sensitive ceramics in all three formulations. Interestingly, the glass-ceramic coating 3# containing Y2O3 demonstrated an increase in electrical resistance. Both the NTC thermistors coated with 1# and 2# glass formulations successfully passed 1000 thermal shock cycles without visible failures, and their resistance change ratios were well below the requisite 20%.

Thermophysical Properties of Glass-Ceramic Coatings of PbO–ZnO–B$_2$O$_3$ System Doped with Al$_2$O$_3$, SiO$_2$, and BaO Oxides

Thermophysical Properties of Glass-Ceramic Coatings of PbO–ZnO–B$_2$O$_3$ System Doped with Al$_2$O$_3$, SiO$_2$, and BaO Oxides