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Abstract A multilayer Re/Ir coating was deposited on WC substrate by RF magnetron sputtering deposition system. SEM, AFM, XRD, HRTEM, Nano Indenter and contact angle were used to characterize the morphology, micro-structure and anti-sticking property. The results demonstrated that the multilayer Re/Ir coating presented higher anti-sticking property and mechanic performance comparing with the monolayer coatings. The formation of TaC at elevated temperature and coherent boundary between Ta and Ir crystalline were both assumed to impede the further diffusion of C or Co atoms. Moreover, the ordered nanostructure enhanced the bonding between Re and Ir at interface, which made it difficult for Ca, Ba of glass network modifiers elements to penetrate in protective films, and alleviate adhesion of glass at elevated temperature. The motion of edge dislocations and stacking faults were also significantly impeded due to the increase of interfaces and grain boundaries. This restriction probably contributes to improving the mechanical property, which is benefit to the lifetime of mold and the quality of the optical glass product. The wetting angle at high temperature was adopted to evaluate the anti-sticking property of multilayer coating, and shown the coherent results as mentioned before. Highlights • Multilayer Re-Ir coating for glass molding was initially deposited and compared with other monolayer coatings. • The promoted mechanical performance is elucidated by the blockage of dislocations motion. • Atoms diffusion resistance by the interfaces were used to explain the improvement of anti-sticking. [ABSTRACT FROM AUTHOR]

The ultra-smooth surface and hydrophobic nitrogen-incorporated ultra-nano-crystalline diamond (N-UNCD) was directly synthesized by equilibrating the etching effect of OH radical and growth promotion of CN and CH in the 5% CH 4 added H 2 plasma environment with additional feeding of constant 0.16% O 2 and from 0.3% to 3.3% N 2 contents. The initially decreasing and then increasing trend of surface roughness, i.e., from as-grown appearance with pits to smooth and then to worm-like surface, was resulted from the offset and even suppressive effect on OH etched holes by the faster growth rate that under the help of more N 2 promoted chemical groups of CH and CN. In addition, chemical composition, i.e., the large amount of sp 2 phases (sp 2/ sp 3 ratio up to 1.399) and H termination of N-UNCD surface (proportion was 75.54 ± 3.8%), played an another enhancing function for repelling water (contact angle from 81.3° to 93.8°) although the surface roughness decreased to smoothest of 1.36 nm in Root-Mean-Square (RMS) in the presence of N 2 addition from 0.3% to 1%. However, continuing adding N 2 to 3.3%, the formed surface (RMS 8.98 nm) with worm-like ultra-nano diamond crystallites together with higher H reconstructed sp 2 contents (sp 2/ sp 3 ratio rose to 1.478) further boosted the hydrophobicity, at which the contact angle was finally increased to 110.2°. Therefore, in C-H-O-N gas system, ultra-smooth and uniform N-UNCD surface with excellent hydrophobicity can be obtained by a one-step method without any post-treatment. • Ultra-smooth and hydrophobic nitrogen-incorporated UNCD was synthesized in CH 4 /H 2 /O 2 /N 2 system without any post-treatment. • The ultra-smooth nitrogen-incorporated UNCD was obtained by equilibrating the etching effect of OH radical and growth promotion of CN and CH groups. • Hydrophobicity can be enhanced by raised hydrogen reconstructed sp 2 phase although the surface roughness was decreased. [ABSTRACT FROM AUTHOR]

Y 2 O 3 films with different microstructures were deposited through radio frequency magnetron sputtering. The optical properties and the antireflection effects of the cubic and the monoclinic Y 2 O 3 films on diamond substrates were investigated. Results showed that the cubic Y 2 O 3 film had denser and more uniform grains with larger grain size. The band gap energies of the cubic and the monoclinic Y 2 O 3 films were 5.79 and 5.88 eV, respectively. This finding was mainly attributed to the decrease in grain size from 30.1 nm to 20.6 nm. Meanwhile, the reflective indices of the cubic and the monoclinic films were 1.887 and 1.817, respectively. Furthermore, the monoclinic and the cubic Y 2 O 3 films that have the same thickness generated antireflection effects on diamond at the 8–12 μm long-wave infrared (LWIR) range. However, due to the lower reflective index of the monoclinic Y 2 O 3 film compared with that of the cubic Y 2 O 3 film, the maximum antireflection effects of the Y 2 O 3 films on diamond shifted to lower wavelengths. [ABSTRACT FROM AUTHOR]

In this study, the effect of defects on fracture toughness in different directions was investigated. Two diamond films with a diameter of 122 mm and as-deposited thicknesses of 2.2 and 1.5 mm, respectively, were deposited by DC arc plasma jet chemical vapor deposition. To accurately obtain the fracture toughness, the films were ground and polished to 1.6 and 0.8 mm, respectively. The results indicate that many defects, including pores, are introduced into the films during the growth process, particularly on the side close to the growth surface in thicker film. The size of pores reaches micrometres, which affects the fracture toughness under loading in different directions. Due to the minimum grain size, both films exhibit a maximum toughness of 8.2 and 10.0 MPa·m1/2, respectively, with growth-surface cracks. For the thinner sample, the maximum value is followed by that of the edge-surface cracks. As the grain size of the edge surface falls between that of the growth surface and that of the nucleation surface, the results indicate that fracture toughness is affected by grain size. However, the number of pores near the growth side increases when the thickness exceeds 0.8 mm. Pores reduce the toughness, resulting in the minimum fracture toughness (6 MPa·m1/2) of the thicker diamond film with edge-surface laser cracks. The sample with an edge-surface sharp pre-crack has a similar fracture toughness of 5.6 MPa·m1/2. This study provides guidance for selecting the applied load direction. • Two thick diamond films with thicknesses 2.18 and 1.48 mm were deposited. • Fracture toughnesses of the diamond films in three directions were investigated. • Numerous pores were formed in the diamond films during orientation growth. • Due to the effect of pores, the toughness values among three directions differ. [ABSTRACT FROM AUTHOR]