Search

The effects of annealing temperature on the microstructure, mechanical properties, and tribological properties of TiAlSiCN coatings with C contents of 9.24 at.% and 19.45 at.% are systematically investigated. The results show that all coatings maintain cubic structures with strongly preferential orientation of (200) planes, and the microstructure transforms from amorphous embedded in (Ti, Al)(C, N) nanocrystalline to amorphous encapsulated nanocrystalline with increasing C content. Elevating annealing temperature to 800 °C leads to a continuous decline in hardness, whereas the elastic strain resistance H/E increases first and then decreases. Release of H 2 formed by the breaking of the C–H bonds at 400 °C induces a local stress transformation from compressive to tensile. The toughness and hardness decreases dramatically at 600 °C by conversion of sp3 to sp2. The wear mechanisms of the coating against Si 3 N 4 counterballs are adhesive and oxidative wear. The coefficient of friction (COF) and wear rate initially decrease followed by an increase. The coatings with a-C structure exhibit lower COF and the wear process is smoother, but showing higher wear rate. Thus, the annealed TiAlSiCN coatings with preferred C content could improve the mechanical and tribological properties. [ABSTRACT FROM AUTHOR]

The microstructure, mechanical and tribological properties of TiAlSiN coatings with various annealing temperature were studied. Results showed that the oxygen content of the coating raised with the annealing temperature in the range of room temperature to 800 °C, while the hardness decreased monotonically. However, the elastic strain resistance H/E value increased firstly and then decreased. The maximum H/E value of 0.105 was obtained at 400 °C. The deposited coating composed of c-TiN, c-AlN and c-(Ti, Al)N, and Si element mainly existed in the form of SiN x amorphous structure. The adhesive and oxidation erosion were the main wear mechanism against GCr15 steel balls. The coefficient of friction (COF) decreased gradually, but the wear rate increased firstly and then decreased. The minimum wear rate of 1.2 × 10−5mm3/(N·m) was obtained at 400 °C. In addition, oxides including Ti–O, Al–O and Si–O generated on the adhesives play a role of lubricant, which could reduce the shearing resistance and COF of the coating. Therefore, TiAlSiN coatings with optimal annealing temperature has excellent mechanical properties and tribological performance. The research revealed that the annealing temperature has significant effect on the microstructure and properties of TiAlSiN coating. • The TiO 2 oxides, which exists above the detection limit of XRD, are formed at 600 °C. • In addition, the shear resistance and contact area were reduced due to the adhesive Ti–O, Al–O and Si–O composition with low coefficient of friction and high hardness. [ABSTRACT FROM AUTHOR]

The effects of C doping content on the microstructure, mechanical and tribological properties of TiAlSiCN coatings prepared by ion plating are systematically investigated. The results show that the grain is refined with the C content increases to 17.22 at.%, and the (111) and (200) planes present competitive growth, the high C content promotes the preferred orientation of the (200) planes. The hardness of the coating shows a tendency to increase first and then decrease, the coating with C content of 8.15 at.% achieve the highest hardness, while the elastic strain resistance H/E value decreases monotonically. Moreover, it is found that the amorphous carbon (a-C) structure is precipitated with C content above 12.51 at.%. The wear mechanism of the coating against the Si 3 N 4 counterpart is adhesive, and the coefficient of friction (COF) of the coating decreases from 0.4 to 0.2. Thereinto, the reduction in COF is related to the Hertzian contact area as C content below 8.15 at.%. The COF further reduction is attributed to the generation of graphite lubricated structure. However, the wear rate shows first decrease and then increase. Therefore, the preferential C doping content can improve the mechanical and tribological properties of the coatings. • The research revealed that C content has significant effect on the microstructure and tribological properties of TiAlSiCN coating. High C content promotes the preferred orientation of the (200) planes. • The amorphous carbon (a-C) structure is precipitated with C content above 12.54 at.% • The lower COF is related to the Hertzian contact area decrease and the generation of graphite lubricated structure. [ABSTRACT FROM AUTHOR]

The microstructure, mechanical properties, and electrochemical performances of TiCN composite coatings were investigated. Via the modification of the C 2 H 2 /N 2 flow ratio, TiCN coatings with various C contents were synthesized by combining a cathodic arc and glow discharge technology. With a C 2 H 2 /N 2 flow ratio of 1:8, TiCN coating mainly consisted of the TiC phase. As the C 2 H 2 /N 2 flow ratio exceeded 1:4, the crystallinity of TiCN coatings deteriorated. The coexistence of the amorphous and crystalline phases was detected in TiCN coatings with a C 2 H 2 /N 2 flow ratio of 3:8. The introduction of the C element into TiCN coatings could disturb the growth orientation and induce dislocation motion, leading to an enhancive toughness and a decrease in hardness and elastic modulus. Moreover, the precipitation of amorphous C or CN x was beneficial to the corrosion resistance of TiCN coatings. This finding indicates the potential application of TiCN composite coating in corrosive environments. • A high C 2 H 2 /N 2 flow ratio favors the formation of amorphous structures in TiCN coating, and the N atoms preferred to combine with C atoms rather than Ti atoms. • The formation of amorphous structures with a high C 2 H 2 /N 2 flow ratio weakens the hardness of TiCN coating, but the toughness is strengthed. • The inert amorphous structures could endow the TiCN coating with low porosity, and enhance the corrosion resistance. [ABSTRACT FROM AUTHOR]

The microstructure, electrochemical responses, and passive film characteristics of FeCrMoWCBY bulk metallic glasses (BMGs) under Ar+ irradiation were investigated. Under exposure to high irradiation fluence, BMGs retained a large portion of an amorphous structure and exhibited excellent corrosion resistance in 1 mol/l HCl solution. With the enhancive irradiation fluence, the increasing crystal-like clusters and even nanocrystals were gradually precipitated from the exterior amorphous matrix of BMGs. By reducing the proportions of Cr3+/Mo6+/W6+ cations and work functions at the outer passive film, the nano-crystallization destroyed the uniformity and stability of passive films, thus weakening the anti-corrosion capacity of irradiated BMGs. This finding facilitates the potential application of Fe-based BMGs under extreme nuclear-irradiated conditions. [Display omitted] • Fe-based bulk metallic glasses (BMGs) show superior irradiation resistance. • Slight nanocrystals were precipitated at the intense irradiated surface of BMGs. • Heterogeneity destabilized passive films and weakened the anti-corrosion of BMGs. [ABSTRACT FROM AUTHOR]

The microstructure, mechanical properties and tribological properties of CrAlTiN coatings with various atmospheric annealing temperature are systematically investigated. The results show that the hardness of the coating decrease with the annealing temperature increasing from room temperature to 800 °C, however, the elastic strain resistance H/E value increase firstly and then decrease. The deposited CrAlTiN coating is face-centered cubic structure, (111) and (200) planes show competition growth, while high annealing temperature promotes the growth of (200) planes. The main wear mechanisms of CrAlTiN coating against Si 3 N 4 ball are adhesive and oxidative. The coatings annealed at 400 °C has the lowest wear rate and annealed at 800 °C peeled off during the friction process. The chromium oxide, aluminium oxide and titanium oxide with lubricating and high hardness adhered on the wear tracks, playing the role of supporting the counterballs, a low COF of the coating is obtained. The coatings annealed above 600 °C are more easily to form extensive smooth and dense oxide adhesives, but it takes longer to reach stable wear stage. Thus, the preferred annealing temperature could effectively regulate the microstructure and improve the mechanical and tribological properties of CrAlTiN coating. • Annealing temperature has significant effect on the microstructure and properties of CrAlTiN coating. • The coefficient of friction and contact area were reduced due to the oxide adhesives with lubricating and high hardness. • The coatings annealed above 600 °C are more easily to form oxide adhesives. [ABSTRACT FROM AUTHOR]

The tribological properties of diamond-like carbon (DLC) coatings were influenced by their microstructure, which was controlled by the preparation technology and parameters. In this study, Si-DLC coatings were prepared on cemented carbide (YG10C) and stainless steel (316L) substrates by plasma enhanced chemical vapor deposition with various deposition temperatures. The effect of the deposition temperature on the microstructure and tribological properties was systematically investigated. The results showed that the sp3/sp2 values and hardness of the Si-DLC coatings increased firstly and then decreased as the deposition temperature increased from 60 °C to 180 °C, while the tendency in toughness, adhesion strength and residual stress is not consistent with it. The performance of the coatings obtained at 120 °C was best, while the coatings obtained at 150 °C had the lowest toughness due to the volume expansion caused by the transformation of sp3 to sp2. A graphite transfer layer was observed on the wear tracks of friction pairs. Thereinto, O-Si-C on the transfer layer could further reducing shear resistance and plays a role as a lubricant. Therefore, the coating prepared at the preferred deposition temperature had excellent tribological properties. [Display omitted] • The research revealed that the deposition temperature has significant effect on the microstructure and tribological properties of Si-DLC coatings. • The graphite transfer layer was observed on the wear tracks of GCr15 ball. • The O-Si-C bonds on the transfer layer could further reducing shear resistance and plays a role as a lubricant. [ABSTRACT FROM AUTHOR]

The influence of the nitrogen flow rate on the microstructure, mechanical and tribological properties of the CrAlTiN coatings prepared by arc ion plating technology was systematically investigated. The results showed that the content of N and Ti increased, while the deposition rate and grain size decreased with the nitrogen flow rate from 100 sccm increased to 500 sccm. The toughness and adhesion strength firstly increased and then decreased. The coatings showed a cubic NaCl structure, (111) and (200) crystal planes show competition growth, while high nitrogen flow promoted the growth of (200) plane. The main wear mechanisms of CrAlTiN coating against Si 3 N 4 ball were adhesive and chemical erosion. The coefficient of friction decreased with the increase of nitrogen flow rate, but the wear rate firstly decreased and then increased, the coating prepared by using 500 sccm nitrogen flow appeared to peel off the substrate. In addition, the shear resistance and contact area were reduced due to the adhesive Cr–O, Al–O and Ti–O with a low coefficient of friction and high hardness. Therefore, a low coefficient of friction of the coating was obtained. As a result, the CrAlTiN coating prepared by applying optimal nitrogen flow rate had excellent mechanical and tribological performance. • The research revealed that the content of nitrogen has significant effect on the microstructure and properties of CrAlTiN coating. • High nitrogen flow promoted the growth of (200) plane. • In addition, the shear resistance and contact area were reduced due to the adhesive Cr–O, Al–O and Ti–O composition with low coefficient of friction and high hardness. [ABSTRACT FROM AUTHOR]

Amorphous coatings (ACs) with the composition of Fe 49.7 Cr 18 Mn 1.9 Mo 7.4 W 1.6 B 15.2 C 3.8 Si 2.4 were deposited by the arc-spraying technique. The wettability and corrosion performance of Fe-based ACs in 3.5% NaCl solution were investigated using contact angle measurements and electrochemical tests, respectively. Results showed that by controlling the spraying potential, the phase constituent, microstructure, hardness, wettability, and corrosion performance of the coatings were manipulated. With a spraying potential of 26 V, the highly glassy AC exhibited a denser microstructure, higher microhardness, lower surface free energy, and better corrosion resistance than the others. The superior corrosion resistance of the coatings was closely related to the surface hydrophobicity, which was dominantly governed by the microstructure of the coatings. This finding demonstrates the importance of a homogeneous and compact structure for anti-corrosion and provides a quick prediction of corrosion performance among ACs. • The wettability and corrosion resistance of amorphous coatings (ACs) were studied. • The surface wettability of ACs was quantified via the contact angle tests. • This work provided a quick prediction of corrosion performance among ACs. [ABSTRACT FROM AUTHOR]