Papers by Author: Jin Bin Lu

Abstract: Inside the indirect heating chamber, raw material itself is not being electrified nor giving out heat. Instead, heat is offered by some heater outside and transferred inside to heat the raw material indirectly. Gradient of pressure parallels to as well as matches with that of temperature, which solves the mismatch between these two elements inside the high-pressure chamber. Meanwhile, both electrical resistance and temperature remain unchanged when raw material reacts. What described above realizes uniformity and stability of pressure and temperature. During the process of synthesizing diamond, we employ the technology of two-parameter dynamic matching of pressure and temperature. In this way, attached load increases gradually while attached power decreases little by little to keep pressure and temperature in the rich diamond crystal growth area and allow them to move in a restricted area in direction of identical quality line. As a result, pressure and temperature can match dynamically and diamond crystal can grow steadily and continuously in a long time period to produce high-quality product, per unit output reaches as much as 580cts, 60% of which are of high grade.

Abstract: In this paper, the electromagnetic shielding fabric with Ni-Cu-Ni three layers and colorized appearance was prepared by the electroless plating and colorized electroplating. The current density was distributed unevenly in the course of colorized electroplating, which resulted in the nonuniform color of the electroplated fabric. In this paper, this problem was solved by improving the electroplating fixture. The adhesion strength and the conductivity of the coating were measured respectively. The results showed that the Ni-Cu- Ni multilayered coating possessed stronger adhesion strength to the fabric substrate than single layered coating, and the conductivity of coating was better than that of pure metal.

Abstract: TiC reinforced Ni-based composite coating added with 10% TiC and 20% TiC particles were prepared on the surface of Q235 steel by plasma cladding, respectively. SEM as well as EDS and XRD were used to investigate the microstructure and formation mechanism of composite coating. The results show that between composite coating and substrate is metallurgical combination, and the microstructure of composite coating is composed of basic microstructure dendrite γ-Ni, interdendritic eutectic structure (α-Fe+Cr23C6+CrB) and dispersed TiC particle. Part of TiC particles melt when the composite coating added with 10% TiC particles, in the composite coating added with 20% TiC particles, part of TiC particles precipitate after dissolution. TiC particles have a uniform distribution with the size 3~5µm. The maximum value of micro-hardness of composite coating added with 10% TiC and 20% TiC particle is 460 HV0.2 and 620 HV0.2, respectively.

Abstract: The electrochemical corrosion behaviors of Cu60Zr30-xHfxTi10(x=10,15,20) bulk metallic glasses (BMGs) were investigated in 3 mol/L NaOH solution by potentiodynamic polarization experiments and electrochemical impedance spectroscopy (EIS). The results showed that the BMGs had sufficient corrosion resistance in NaOH solution. The anodic showed grading passivation character, and the passivation current density were very low. The corrosion resistance changed with Hf content changing. The passivation current density of Cu60Zr15Hf15Ti10 alloy was lowest and the charge transfer resistance was largest, which means the best corrosion resistance for CuZrHfTi BMGs. Corrosion mechanisms were not changed, while the corrosion resistance decrease after crystallized for the BMGs.

Abstract: TiC reinforced Ni-based composite coating added with 10% TiC particles was prepared on the surface of Q235 steel by plasma cladding. SEM as well as EDS and XRD were used to investigate the microstructure and formation mechanism of composite coating. The results show that between composite coating and substrate is metallurgical combination, and the microstructure of composite coating is composed of basic microstructure dendrite γ-Ni, interdendritic eutectic structure (α-Fe+Cr₇C₃+Fe₃C) and dispersed TiC particle. The maximum value of micro-hardness of composite coating added with 10% TiC particle is 440 HV_0.2.

Abstract: TiC reinforced Fe-based composite coating with 10% and 20% TiC particle were prepared on the surface of substrate Q235 steel by plasma cladding, respectively. The microstructure and formation mechanism of cladding layer were carefully investigated by SEM, EDS and XRD. The results show that metallurgical combination is achieved between coating and substrate, the microstructure of composite coating is composed of dendrite α-Fe, interdendritic eutectic structure (α-Fe, Cr23C6 and CrB) and added TiC particles, and microstructure refinement with the increase of TiC particles content. TiC particles react with Fe-based alloy and part of TiC particles dissolve into coating. The hardness of composite coating has a relationship with TiC particles content and TiC particles distribution, and hardness increase with the increase of TiC particles content. The maximum value of composite coating hardness is 545 HV0.2 and 719 HV0.2, respectively. The major strengthening mechanism is fine-grain strengthening, solid solution strengthening and dispersion strengthening.

Abstract: Mono-crystal diamond was brazed with Ni-Cr alloy in protective atmosphere furnace, SEM and XRD were used to analyze the carbides on the surface of diamond and the phases of diamond after brazing, respectively. The results show that the diamond brazed in protective atmosphere furnace can realize high strength connection; the diamond has clear edges and complete morphology after brazing. On the surface of diamond, the arrangement of Cr₃C₂ is regular, the growth direction of Cr₃C₂ has a certain orientation relationship with the (111) crystal plane of diamond, all the Cr₇C₃ nucleates and grows on the surface of Cr₃C₂, finally, the inner layer is regular arrangement Cr₃C₂ and the external layer is Cr₇C₃.

Abstract: Samples of high temperature brazing diamond with Ni-Cr alloy are prepared in protective atmosphere furnace for brazing time is 1 minute, 2 minutes, and 5 minutes. The microstructures were analyzed with Scanning electron microscope, energy dispersive spectroscopy and X-ray diffraction. The results show that there are two layers of carbides on the surface of diamond, lamellar carbide Cr3C2 and columnar carbide Cr7C3, the growth direction of Cr3C2 has a certain orientation relationship with the crystallographic plane of diamond, and Cr7C3 nucleates on the surface of Cr3C2. With the increase of brazing time, the morphology of carbide Cr3C2 turns from linear to lamellar and carbide Cr7C3 turns from granule to columnar. After brazing, chemical metallurgical combination is achieved between diamonds and brazing alloy and carbides are the primary reason for the strong bond strength.