Search Results (77)

The laser cladding (LC) of titanium matrix composite coatings (TMCCs) on titanium components not only effectively enhances the wear resistance, fatigue resistance, corrosion resistance, and biocompatibility of titanium and its alloys, but also circumvents the incompatibility and low bonding strength issues associated with other metallic composite coatings. While the incorporation of ceramic particles is a critical strategy for improving the coating performance, the limited interfacial bonding strength between ceramic particles and the matrix has historically constrained its advancement. To further elevate its performance and meet the demands of components operating in harsh environments, researchers worldwide have employed LC to synthesize in situ hard ceramic reinforcements such as TiC, TiB, TiN, and others within TMCCs on titanium substrates. This approach successfully addresses the aforementioned challenges, achieving coatings that combine a high interfacial bonding strength with superior mechanical properties. This paper provides a comprehensive review of the processing techniques, phase composition, microstructure, and mechanical properties of in situ-synthesized ceramic-reinforced TMCCs via LC on titanium components, with a focused summary of their strengthening mechanisms. Furthermore, it critically discusses the challenges and future prospects for advancing this technology. Full article

The aim of the present research was to synthesize protective composite layers from biodegradable cellulose and biocompatible, sol–gel-derived silica cryogel. An important task in the present work was to achieve good applicability on distinct (smooth and rough) surfaces of various materials (from metallic to ceramic). The aim was to utilize the composite layers as thermal and electric insulation coating. The investigation put some effort into the enhancement of mechanical strength and the elasticity of the thin layer as well as a reduction in its water solubility. The removal of the alkali content leads successfully to a significant reduction in water solubility (97 wt% → 1–3 wt%). Adhesion properties were measured using a specialized measurement technique developed in our laboratory. Treatments of the substrate surface, such as alkaline or acidic etching (i.e., Na₂CO₃, HF, water glass), mechanical roughening, or the application of a thin alkali-containing primer layer, strongly increase adhesion. SEM analyses revealed the interactions between the matrix and the reinforcement phase and their morphology. Full article

Composite electrodeposited coatings hold significant potential for marine and aerospace applications due to their synergistic corrosion resistance and wear durability, yet nanoparticle agglomeration and interfacial incompatibility persistently undermine their performance. Conventional dispersion techniques—mechanical agitation, surfactants, or high-energy methods—fail to resolve these issues, often introducing residual stresses, organic impurities, or thermal damage to substrates. This study addresses these challenges through a novel thermal-assisted alkaline etching (TAE) protocol that synergistically removes surface oxides and enhances colloidal stability in β-SiC nanoparticles. By combining NaOH-based etching with low-temperature calcination (250 °C), the method achieves oxide-free SiC surfaces with elevated hydrophilicity and a ζ-potential of −25 mV, enabling submicron clustering (300 nm) without surfactants. Electrodeposited Co/SiC coatings incorporating TAE-SiC exhibited current-modulated reinforcement, achieving optimal SiC incorporation (5.9 at% Si) at 8 A/dm² through electrophoretic–hydraulic synergy, along with uniform cross-sectional distribution validated by SEM. Tribological assessments revealed shorter wear tracks in TAE-SiC-enhanced coatings compared to their untreated counterparts, suggesting enhanced interfacial coherence despite a comparable mass loss. Demonstrating scalability through cost-effective aqueous-phase chemistry, this methodology provides a generalized framework applicable to other ceramic-reinforced systems (e.g., Al₂O₃ and TiC), offering transformative potential for next-generation protective coatings in harsh operational environments. Full article

Carbon fiber-reinforced composites (CFRCs) have attracted considerable attention in recent years due to their excellent properties, enabling their use across various sectors. However, their application at high temperatures is limited by the fibers’ lack of oxidation resistance. This study demonstrates a significant advancement in enhancing the oxidation stability performance of carbon fiber-reinforced composites (CFRCs) by developing a silicon carbide (SiC) coating through the ceramization of carbon fibers using silicon (Si) powder. For the first time, this method was applied to recycled carbon fibers from CF thermoplastic composites. The key findings include the successful formation of a uniform SiC coating, with coating thickness increasing with process duration and decreasing at higher temperatures. The treated fibers exhibited substantially improved oxidation resistance, maintaining structural stability above 700 °C—markedly better than that of their uncoated counterparts. Thermogravimetric analysis confirmed that oxidation resistance varied depending on the CF/Si ratio, highlighting this parameter’s critical role. Overall, this study offers a viable pathway to enhance the thermal durability of recycled carbon fibers for high-temperature applications. Full article

Using low-cost transition-metal chlorides and furfuryl alcohol as raw materials, the (TiZrHfNbTa)C precursor was prepared, and a three-dimensional braided carbon fiber preform (C/C) coated with pyrolytic carbon (PyC) was used as the reinforcing material. A C/C-(TiZrHfNbTa)C composite was successfully fabricated through the precursor impregnation pyrolysis (PIP) process. Under extreme oxyacetylene ablation conditions (2311 °C/60 s), this composite material demonstrated outstanding ablation resistance, with a mass ablation rate as low as 0.67 mg/s and a linear ablation rate of only 20 μm/s. This excellent performance can be attributed to the dense (HfZr)₆(TaNb)₂O₁₇ oxide layer formed during ablation. This oxide layer not only has an excellent anti-erosion capability but also effectively acts as an oxygen diffusion barrier, thereby significantly suppressing further ablation and oxidation within the matrix. This study provides an innovative strategy for the development of low-cost ultra-high-temperature ceramic precursors and opens up a feasible path for the efficient preparation of C/C-(TiZrHfNbTa)C composites. Full article

Nano-titanium dioxide ceramic coatings exhibit excellent wear resistance, corrosion resistance, and self-cleaning properties, showing great potential as multifunctional protective materials. This study proposes a synergistic reinforcement strategy by encapsulating micron-sized Al₂O₃ particles with nano-TiO₂. A core-shell structured nanocomposite coating composed of 65 wt% nano-TiO₂ encapsulating 30 wt% micron-Al₂O₃ was precisely designed and fabricated via a slurry dip-coating method on Q235 steel substrates. The microstructure and surface morphology of the coatings were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Comprehensive performance evaluations including densification, adhesion strength, wear resistance, and thermal shock resistance were conducted. Optimal coating properties were achieved under the conditions of a binder-to-solvent ratio of 1:15 (g/mL), a heating rate of 2 °C/min, and a sintering temperature of 400 °C. XRD analysis confirmed the formation of multiple crystalline phases during the 400 °C curing process, including titanium pyrophosphate (TiP₂O₇), aluminum phosphate (AlPO₄), copper aluminate (Cu(AlO₂)₂), and a unique titanium phosphate phase (Ti₃(PO₄)₄) exclusive to the 2 °C/min heating rate. Adhesion strength tests revealed that the coating sintered at 2 °C/min exhibited superior interfacial bonding strength and outstanding performance in wear resistance, hardness, and thermal shock resistance. The incorporation of nano-TiO₂ into the 30 wt% Al₂O₃ matrix significantly enhanced the mechanical properties of the composite coating. Mechanistic studies indicated that the bonding between the nanocomposite coating and the metal substrate is primarily achieved through mechanical interlocking, forming a robust physical interface. These findings provide theoretical guidance for optimizing the fabrication process of metal-based ceramic coatings and expanding their engineering applications in various industries. Full article

This study elucidates the dynamic tribo-mechanical response of laser-cladded FeNiCr-B₄C metal matrix composite (MMC) coatings on AISI 1040 steel substrate, unraveling the intricate interplay between microstructural features and phase transformations. A multi-faceted approach, employing high-resolution scanning electron microscopy (SEM) and advanced X-ray diffraction/Raman spectroscopy techniques, provided a comprehensive characterization of the coatings’ behavior under mechanical and scratch testing, shedding light on the mechanisms governing their wear resistance. Specifically, microstructural analysis revealed uniform coatings with a columnar structure and controlled defect density, showcasing an average thickness of 250 ± 20 μm and a transition zone of 80 ± 10 μm. X-ray diffraction and Raman spectroscopy confirmed the presence of α-Fe (Im-3m), γ-FeNiCr (Fm-3m), Fe₂B (I-42m), and B₄C (R-3m) phases, highlighting the successful incorporation of B₄C reinforcement. The addition of 5 and 7 wt.% B₄C significantly increased microhardness, showing enhancements up to 201% compared to the B₄C-free FeNiCr coating and up to 351% relative to the AISI 1040 steel substrate, respectively. Boron carbide addition promoted a synergistic strengthening effect between the in situ formed Fe₂B and the retained B₄C phases. Furthermore, scratch test analysis clarified improved wear resistance, excellent adhesion, and a tailored hardness gradient. These findings demonstrated that optimized short-pulsed laser cladding, combined with moderate B₄C reinforcement, is a promising route for creating robust, high-strength FeNiCr-B₄C MMC coatings suitable for demanding engineering applications. Full article

In this paper, the preparation of Ni60 + WC/NbC composite coating by laser cladding technology was studied. The coating properties were analyzed by a scanning electron microscope (SEM), an energy dispersion spectroscope (EDS), X-ray diffraction (XRD), a hardness tester, and a friction and wear tester. The results show that WC and NbC, as two typical ceramic reinforcing phases, play a positive role in improving the wear resistance and hardness of the coating. Under the action of a high-temperature (about 2500 °C) laser beam, some complex compounds, such as Ni₃Fe and M₂₃C₆ (M=Fe, Cr) are formed in the coating, which leads to the left deviation of XRD peak position. With the decrease in WC and the increase in Nb particles, the wear mechanism of the coating changes from abrasive wear to adhesive wear. When adding 10% WC, the microhardness of the coating reaches 809.5 HV, the coefficient of friction is 0.496, and the wear rate is 1.1804 × 10⁻⁷ mm³ N⁻¹·m⁻¹, which shows the best wear resistance. Full article

Prior to the laser processing, the surface of the TiC-reinforced particles underwent a metallization process with Ni-P, with the objective of enhancing the wettability between the TiC and the Ti6Al4V, thereby ensuring enhanced wear resistance of the titanium-based composite (TMC) coatings. In this study, the chemical deposition method was utilized to synthesize three types of metallized TiC with varying phosphorus contents. The P contents of these samples were determined to be 9.12 wt.% (HP metallized TiC), 6.55 wt.% (MP metallized TiC), and 1.71 wt.% (LP metallized TiC). It was observed that the thickness of the coatings increased in a gradual manner with the decrease in P. Furthermore, the coating of the LP metallized TiC was found to possess the highest degree of crystallinity and a microcrystalline structure. The 50 wt.% TiC-Ti6Al4V composite coatings (TMC-Nickel-free, TMC-HP, TMC-MP, and TMC-LP) were produced by laser fusion deposition using untreated TiC and three metallized TiC enhancements. The findings indicate that TMC-LP exhibits cracking only during the initial processing stage. Surface metallization has been shown to enhance the wear resistance of composite coatings through several mechanisms, including increased bonding of the ceramic phase to the metal matrix and the formation of hard Ti₂Ni compounds. The wear rates of TMC-HP, TMC-MP, and TMC-LP were reduced by 22%, 43%, and 72%, respectively, in comparison to TMC-Nickel-free. Full article

In this paper, polymethylhydrosiloxane (PMHS) and ethanol were used as raw materials to synthesize the ceramic precursor of side ethoxy polysiloxane (PESO) using dehydration and a dealcoholization reaction, which had a ceramic yield of 87.15% and a very low residual carbon content. With the quartz fiber as a reinforcer, the silica matrix composites (SiO_2f/SiO₂) with a double-layer interface (PyC-SiO₂/BNNSs) coating were manufactured using precursor impregnation pyrolysis (PIP). The as-prepared SiO_2f/SiO₂ possessed an excellent mechanical property, which exhibited obvious fiber pull-out and debonding phenomena from a fracture morphology. The flexural strength and fracture toughness of SiO_2f/SiO₂ reached 63.3 MPa and 2.52 MPa·m^1/2, respectively. Moreover, the SiO_2f/SiO₂ had suitable dielectric properties, with a dielectric constant of about 2.5 and a dielectric loss of less than 0.01. This work provides an important concept for the enhancement of the dielectric properties and mechanical properties of quartz fiber-reinforced ceramic matrix composites, as well as in the preparation of wave-transmissivity composites. Full article

To fulfill the harsh surface demand for key industrial components, metal matrix composite coatings (MMC) with hard ceramic particles located in the metallic matrix have attracted considerable attention in recent years. In this paper, WC/Stellite-6 composite coatings were fabricated via supersonic laser deposition (SLD). The effects of laser heating temperature, WC particle size and addition content on the deposition characteristics were systematically studied. The microstructures and mechanical properties of the as-prepared composite coatings were examined. The results demonstrated that increasing laser heating temperature can improve powder deposition efficiency for both coarse and fine WC-reinforced coatings. The peak coating height of fine WC-reinforced composite coating is 1157 μm, which is higher than that of coarse WC-reinforced composite coating (505.5 μm) deposited under the same laser heating temperature. The increase in laser heating temperature and WC addition content in original composite powder resulted in the increase in WC fraction in the composite coating, which can achieve a highest value of 55.9 vol.%. The SLD composite coating had comparable bonding strength (145.5 MPa) to that of laser cladded (LC) coating. The SLD specimen showed plastic fracture behavior, which was different from brittle fracture behavior for the LC sample. Full article

Low-pressure cold-spray (LPCS) aluminum is widely used for coating depositions in various engineering applications but is limited by its low hardness and poor wear resistance. To improve these properties, ceramic particles are added to form metallic matrix composites (MMCs). High-pressure processes can achieve effective MMC coatings but are costly and energy intensive. LPCS has been studied to develop an Al-based MMC at a lower cost. To ensure the adaptation of developed LPCS coating in engineering applications, the behavior of the coating under certain loads needs to be established. This study investigates the sliding wear behavior, friction characteristics, hardness, and microstructure of Al-Al₂O₃ and Al-Al₂O₃/TiN composite coatings deposited using LPCS at 1 MPa and 450 °C. The effect of adding 25 wt% TiN to the Al-Al₂O₃ composite was explored. Although the addition of TiN did not significantly enhance the hardness of the coating, SEM analysis revealed notable differences in wear behavior between the two coatings. The Al-Al₂O₃/TiN composite exhibited better wear resistance, which was attributed to the reduced formation of powdery wear debris and improved crack suppression. These findings highlight the potential of TiN reinforcement to enhance the tribological performance of LPCS aluminum-based coatings, offering a promising solution for improving wear resistance in engineering applications. Full article

High-hardness iron-based alloy coatings are extensively utilized in aerospace, automotive, and industrial equipment due to their exceptional wear resistance and long service life. Laser cladding has emerged as one of the primary techniques for fabricating these coatings, owing to its rapid cooling and dense microstructure characteristics. However, the production of high-hardness iron-based alloy coatings via laser cladding continues to face numerous challenges, particularly when controlling the morphology, quantity, and distribution of the reinforcing phases, which can lead to cracking during processing and service, thus compromising their usability. The cracks of the cladding layer will be suppressed through good microstructure design and control, resulting in a wide range of performance for high-hardness Fe-based alloy coatings. This paper reviews recent advancements in the design and control of the organization and structure of high-hardness iron-based alloy coatings from the perspectives of material composition, processing parameters, and external assistance techniques. It summarizes the properties and applications of various materials, including different alloying elements, ceramic particles, and rare earth oxides, while systematically discussing how processing parameters influence microstructure and performance. Additionally, the mechanisms by which external auxiliary energy fields affect the melt pool and solidified microstructure during laser cladding are elucidated. Finally, the future development directions of laser cladding technology for high-hardness iron-based coatings are anticipated, emphasizing the need for further quantification of the optimal coupling relationships among the gain effects of composite energy fields. Full article

The primary characteristic of ablative materials is their fire resistance. This study explored the development of cost-effective ablative materials formed into application-specific shapes by using a polymer matrix reinforced with ceramic powder. A thermoplastic (polypropylene; PP) and a thermoset (polyester; UPE) matrix were used to manufacture ablative materials with 50 wt% silicon carbide (SiC) particles. The reference composites (50 wt% SiC) were compared to those with 1 and 3 wt% short glass fibers (0.5 mm length) and to composites using a 1 and 3 wt% glass fiber mesh. Fire resistance was tested using a butane flame (900 °C) and by measuring the transmitted heat with a thermocouple. Results showed that the type of polymer matrix (PP or UPE) did not influence fire resistance. Composites with short glass fibers had a fire-resistance time of 100 s, while those with glass fiber mesh tripled this resistance time. The novelty of this work lies in the exploration of a specific type of material with unique percentages of SiC not previously studied. The aim is to develop a low-cost coating for industrial warehouses that has improved fire-protective properties, maintains lower temperatures, and enhances the wear and impact resistance. Full article

Shells are primarily composed of calcite and aragonite, making the inclusion of micronized shells as bio-based fillers in organic coatings a potential means to enhance the mechanical properties of the layers. A water-based coating was reinforced with 5 wt.% Acanthocardia tuberculata powder, 5 wt.% Mytilus galloprovincialis powder, and 5 wt.% of an LDPE/ceramic/nanoceramic composite. An improvement in abrasion resistance was achieved using micronized seashells, as demonstrated by the Taber test (evaluating both weight loss and thickness reduction). Additionally, Buchholz hardness improved with powders derived from Mytilus galloprovincialis. No significant differences were observed among the samples in terms of color and gloss after 200 h of UV-B exposure. However, the delamination length from the scratch after 168 h of exposure in a salt spray chamber indicated that the addition of particles to the polymeric matrix resulted in premature degradation, likely due to the formation of preferential paths for water penetration from the scratch. This hypothesis was supported by electrochemical impedance spectroscopy measurements, which revealed a decrease in total impedance at 0.01 Hz shortly after immersion in a 3.5% NaCl solution. In conclusion, the particle size and shape of the micronized shells improved abrasion resistance without altering color and gloss but led to a decrease in the coating’s isolation properties. Full article