The wear and corrosion of cemented carbides pose substantial challenges to maintaining the reliability and extending the service life of marine engineering equipment under severe maritime conditions. In this study, a self-enhanced magnetron sputtering system combined with a straight-tube filtered cathode vacuum arc deposition system was employed to fabricate tetrahedral amorphous carbon (ta-C) coatings on cemented carbides. Four distinct coatings were prepared using a 70 A direct current power supply and a pulsed direct current power supply with peak currents varying from 300 to 500 A. The results indicate that the application of pulsed current power significantly improves the surface quality of the coatings and increases their sp3 content. As the peak pulse current increases, the energy of C ion bombardment gradually rises, leading to a trend in which the mechanical and physical properties of ta-C coatings initially improve before declining. The coating prepared with a peak current of 400 A exhibits the best wear rate (3.6 x 10-6 mm3 center dot N- 1 center dot m- 1) and the best electrochemical stability (open current potential = -0.3 V), which can be attributed to its superior coating composition (sp3 fraction = 72 %), improved resistance to plastic deformation (H3/E*2 = 0.8 GPa) and fewer coating defects.

Multilayer cBN/NCD (cubic boron nitride and nano-crystalline diamond) composite coating with modulation periods of 1 mu m, 1.5 mu m and 3 mu m were deposited by anode layer linear ion source assisted radio frequency magnetron sputtering (ALLIS-RFMS) and microwave plasma chemical vapor deposition(MPCVD) on cemented tungsten tools (YG6) and Si substrates. The microstructures, mechanical and tribological properties of the multilayer composite coating were systematically characterized and investigated. In this work, with a decrease of modulation periods, the surface roughness of cBN/NCD multilayer composite coatings exhibited an increasing trend, but the mechanical properties were improved significantly. When the modulation period decreases to 1 mu m, the residual stress of the composite coating can be reduced to -0.61 GPa, fracture toughness increased to 4.81 MPa center dot m(1/2). Friction and wear tests demonstrated that the wear resistance of the multilayer cBN/NCD composite coating was related to the residual stress and fracture toughness, the friction coefficient keep a stable values about 0.12-0.15, the wear rate decreased significantly with decreasing modulation period, and the lowest wear rate was about 3.69 x 10(-6) mm(3)/(N center dot m) when the modulation period is 1 mu m. The work suggests that decreasing the modulation period is an effective way to improve the mechanical and tribological properties of multilayer cBN/NCD composite coating.

To improve the longevity of medical devices in physiological environments, a series of TiZrNbTaMoCxNy coatings were fabricated on 316L stainless steel using RF magnetron sputtering. The work demonstrated that appropriate carbon doping can effectively enhance the density, electrochemical properties, and resistance to tribo-corrosion of the coatings. Among the tested samples, coating S4 with a carbon content of 24 at. % exhibited the lowest wear rate (6.496 x 10- 7 mm3 N-1 m-1) during the tribo-corrosion tests, due to its favorable lubrication characteristic (COF = 0.127) and enhanced resistance to plastic deformation (H3/E2 = 0.78 Gpa). Additionally, coating S5 with a carbon content of 28 at. % showed superior electrochemical performance (icorr = 5.21 x 10-8 A), attributed to its higher coating density and ability to form passive films. Both S4 and S5 exhibited superior biocompatibility compared to 316L.

The reaction process of ZrC-2ZrB2-based Cu cermets from the (1 -xwt.%)(1B4C-3Zr)-x wt.%Cu system (Zr/B4C = 3 in molar ratio) was explored. Results showed that ZrC and ZrB2 were mostly produced through the dissolution of B4C into a preformed Zr-Cu liquid. With an increase in x, the synthetic ZrC-2ZrB2 and generated heat were reduced. This effect decreased an ability for Zr-Cu liquid to propagate in the reactants, and restrained the dissolution Zr. As a result, the complete synthesis of ZrC-2ZrB2 failed in the systems with a higher Cu content (e.g., 50 wt.%). Furthermore, after the precipitation of ZrC and ZrB2, the liquid surrounding would prevent ZrC and ZrB2 from growing. Increasing Cu content enhanced the amount of Zr-Cu melt. This behavior contributed to a decline in ZrC-2ZrB2 particle sizes, and the production of fine ceramic particles (-200 nm). It is also revealed that the formation of ZrC-2ZrB2 is a multistep process, which results in the inhomogeneity of ZrC-2ZrB2 particle sizes. A valuable approach was proposed to explore the relationship between reaction process and synthesized products of combustion synthesis-related technique. [doi:10.2320/matertrans.MT-M2022210]

采用高功率脉冲磁控溅射方法在不同基体偏压下的钢基体上沉积含Cr过渡层的DLC薄膜.利用原子力显微镜、场发射扫描电镜、Raman光谱、动态超显微硬度计和划痕仪对薄膜的表面形貌、截面形貌、结构成分、力学性能进行表征.结果表明:随着基体偏压的增大,薄膜表面更加平整,表面粗糙度减小;不同基体偏压下制备的DLC薄膜与基体结合良好,厚度均匀,结构致密;Raman结果显示,ID/IG值随基体偏压的增大不断下降,薄膜中sp3含量逐渐增加;当基体偏压增大时,薄膜硬度和弹性模量均呈上升趋势,膜基结合强度增加.

In this paper, the free-standing diamond (FSD) and microcrystalline diamond (MCD) film were etched by double-bias assisted hot filament chemical vapor deposition (HFCVD) to prepare two kinds of diamond cone array tools (DCATs) for precision processing. It is the first time to use free-standing diamond cone array tool (FSD-CAT) and microcrystalline diamond cone array tool (MCD-CAT) to perform the lapping processing experiment for monocrystalline silicon and to carry out the performance evaluation of DCAT. The surface roughness of the silicon lapped by FSD-CAT is 28.9 nm, and the surface roughness of the silicon lapped by MCD-CAT is 18 nm. By using the combination of both DCATs to lapped silicon, a smooth surface with a surface roughness of 5 nm is obtained. By comparing the surface roughness of monocrystalline silicon which lapped by diamond tools with and without etching, because of the smaller cross-section of the cones cut into the surface of monocrystalline silicon, DCAT can effectively reduce the Surface roughness of the silicon.

Diamond-like carbon (DLC)/CrN multilayer composite films with different modulation ratios were prepared by high power pulsed magnetron sputtering (HPPMS). The strengthening mechanism of tribological properties and corrosion resistance of multilayer DLC films were detailedly discussed. The results showed that the single layer DLC film peeled off after 25 min of friction, while the DLC/CrN multilayer films exhibited good wear resistance. The furrow phenomenon of wear track weaken, the depth of wear track decreased, and the wear resistance of the film enhanced with the increase of modulation ratio. The wear resistance of DLC film is directly related to its hardness, plastic deformation resistance and residual internal stress, and the DLC/CrN multilayer film with modulation ratio of 2:1 had the best wear resistance. Electrochemical experiments show that improving the density of the film, inhibiting the formation of corrosion ion diffusion channel and forming passive film at the interface are important factors to enhance the corrosion performance, and the DLC/CrN multilayer film with modulation ratio of 1:1 film had the best corrosion properties.

Diamond-like carbon (DLC) films with bias-graded increments of 5 V, 10 V, and 20 V were prepared by adjusting the substrate bias voltage in a high-power pulsed magnetron sputtering system (HPPMS). The microstructural, mechanical, tribological, and electrochemical corrosion properties of DLC films were systematically investigated. In this work, the sp3 content in the DLC film with a constant bias of-200 V was the highest, and the sp3 content in the bias-graded DLC film exhibited a gradient increasing trend. Bias-graded DLC films had lower hardness, elastic modulus and residual stress than DLC film with a constant bias of-200 V. With a decrease in bias-graded increment, the ratio of hardness to elastic modulus increased. Friction and wear tests demonstrated that the wear resistance of the DLC film was related to the hardness, residual stress and ratio of the hardness to the elastic modulus. The wear rate decreased with decreasing bias-graded increment, and the DLC film with a bias-graded increment of 5 V had the lowest friction coefficient and wear rate, which were 0.077 and 6.74 x 10- 7 mm3/Nm, respectively. The polarization curve results revealed that the DLC film with constant bias had the highest corrosion potential and corrosion current density. As the bias-graded increment increased, the corrosion po-tential and corrosion current density showed an increasing trend. Combined with the electrochemical impedance spectroscopy results, the bias-graded DLC films with bias-graded increments of 5 V and 10 V exhibited better corrosion resistances.

In order to obtain diamond-like carbon (DLC) coatings with excellent corrosion resistance, soft (low sp(3) content) and hard (high sp(3) content) alternating multilayer DLC films were prepared on silicon wafers by high power pulsed magnetron sputtering (HiP-IMS), and the influence of modulation ratio on the corrosion resistance of the films was investigated. X-ray photoelectron spectroscopy (XPS), four-probe resistance meter and surface profilometer were used to test composition, resistivity and residual stress of films. The polarization curve of the multi-layer DLC film were obtained through electrochemical experiment tests to study the effects of modulation ratio on the corrosion resistance of the films. Results show that compared with the low bias voltage(-25 V), the sp(3) content of the DLC film deposited under high bias voltage(-75 V) is significantly increased. The resistivity of pure soft film is 100.53 k Omega.cm, and the resistivity of pure hard DLC film was as high as 1 585.21 k Omega.cm, the resistivity increased with the increase of the hard film thickness. The residual stress in the film increased with the modulation ratio (soft : hard) decreased. Electrochemical experimental results show that the self-corrosion potential of the multilayer DLC film with a modulation ratio of 1:2 is -0.014 V, the self-corrosion current density is 36.6 nA/cm(2), and the multilayer DLC film has relatively optimal corrosion resistance. Results show that the alternating hard and soft multilayer structure can effectively reduce the residual stress in DLC films, the DLC films with excellent corrosion resistance can be obtained by reasonably adjusting the multilayer structure of films and the sp(3) content in the films.

介绍了"新工科"提出的背景及南京航空航天大学机械工程专业的发展历程.探讨了"新工科"背景下的机械工程专业的发展要求,提出了在"新工科"背景下,机械工程专业的阶梯式模块化知识体系和"三个结合"多元化的制造技术人才能力培养机制,为培养出具有较高科学素养、创新能力、社会担当能力的机械工程专业高质量人才奠定了基础.