The Ningbo Branch of Ordnance Science institute of China

Ningbo, China

The Ningbo Branch of Ordnance Science institute of China

Ningbo, China
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Zhong Q.,Taiyuan University of Technology | Hei H.-J.,Taiyuan University of Technology | Li X.-J.,The Ningbo Branch of Ordnance Science Institute of China | Zhang A.-L.,Beijing Institute of Control Engineering | And 3 more authors.
Rengong Jingti Xuebao/Journal of Synthetic Crystals | Year: 2016

The diamond films were deposited on 65 mm diameter Si substrates by a self-designed microwave plasma chemical vapor deposition (MPCVD) system with input power of 8 kW. The effect of the gas inlet and outlet location on the film thickness and quality uniformity was investigated. The thickness and the quality of the diamond films were characterized by digital micrometer and Raman spectrometer, respectively. Comsol software was adopted to simulate the gas flow field in the cavity with different gas inlets and outlets. The results indicated that the gas-inlet and gas-outlet locations did not impact the plasma state, but would cause serious thickness and quality problems of diamond films. When the gas was introduced into the cavity from the gas inlet embed in the wall of the middle chamber, both the thickness and quality of the diamond films are non-uniform. Nevertheless, when the gas was introduced from the coaxial inner conductor center, the uniformity of both was improved. Moreover, when the gas was departed from the bottom of the cone-shaped reflector, the best uniformity could be obtained. The non-uniformity of the gas flow field and the different flow rate at the plasma region are the main reason for the thickness and quality non-uniformity of the diamond films. © 2016, Chinese Ceramic Society. All right reserved.


Ni P.,The Ningbo Branch of Ordnance Science Institute of China | Wang J.,AVIC China Aerospace Polytechnology Establishment | Yan M.,AVIC China Aerospace Polytechnology Establishment | Zheng S.,Aerospace Science & Industry Defence Technology nter
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2017

The technical theory of digital radiography mainly includes three aspects: the image quality representation, the theory of detail recognition, and the control theory of testing technology. In recent years, the testing image quality parameters are concerned by foreign correlative research. In China, the testing image quality parameters are fully discussed, the theory of detail recognition is systematically given from the visual characteristic law, and the technology of image digital control is introduced into the control theory of testing technology. Equivalence assessment is a question that needs to be solved and answered, when the film radiography technology is replaced by digital radiographic testing. In foreign countries, the comparison test is carried out. In China, the theory of imaging process is introduced, and a simple method is given to deal with the problem of technical standard and system equivalence. © 2017 Journal of Mechanical Engineering.


Li X.-J.,The Ningbo Branch of Ordnance Science Institute of China | Gao Y.-L.,The Ningbo Branch of Ordnance Science Institute of China | Yang L.-H.,Shenyang Institute of Architectural Design | Zheng S.-Q.,The Ningbo Branch of Ordnance Science Institute of China
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2015

Aluminized layer was prepared on the industrial pure copper surface by powder embedding method, in order to further improve the strengthening effect, the layer was treated by solution treatment, aging and cryogenic heat treatments. The microstructure, hardness, wear resistance, corrosion resistance and oxidation resistance of the aluminized layer after heat treatment were studied. The results show that, the metallographic microstructure of aluminized layer is α+(α+γ2) phase. After solution treatment, the β' phase can be observed with acicular structure which is similar with martensite. After cryogenic treatment, the β' phase become more tiny, and the exsolution of β' occurred during aging treatment (at 300℃), a large number of dispersed second phase can be seen. After heat treatment, the hardness, wear resistance, corrosion resistance and oxidation resistance of the aluminized copper have been improved significantly. After the process of solution treatment+liquid nitrogen cooling directly+aging treatment, the hardness reaches up to 145.9 HRF. The second phase will diffuse during the aging treatment, which is beneficial to improve the wear resistance, and the corrosion resistance of the aluminized layer has improved one order of magnitude than pure copper. The aluminized copper with small and compact microstructure has better oxidation resistance after heat treatment, which will restrain the surface oxidation effectively. The complex heat treatment process for aluminized layer on pure copper adopted in this research, which is helpful to improve its using performance obviously, and this technic has very important practical application value. © 2015, Editorial Office of Transactions of Materials and Heat Treatment. All right reserved.


Hei H.,Taiyuan University of Technology | Ma J.,Taiyuan University of Technology | Li X.,The Ningbo Branch of Ordnance Science Institute of China | Yu S.,Taiyuan University of Technology | And 3 more authors.
Surface and Coatings Technology | Year: 2015

In this paper, bi-layer (SiC+diamond) coatings were synthesized on 0.8-mm-diameter cemented carbide micro-end mills. The influences of SiC interlayers and diamond coatings on the morphologies, phase composition and fracture strength were investigated. The cutting performance of the bi-layer (SiC+diamond) coated tools was validated by dry cutting of aluminum alloys. The results indicated that the binder Co reacted with SiC to form cobalt silicides (i.e., Co2Si and CoSi), suggesting that the SiC interlayer suppressed the deleterious effects of Co, successfully. Neither the presence of the SiC interlayer nor the bi-layer coatings reduced the fracture resistance of the tools. The workpieces had a better surface finish after being cut by the coated tools than those cut by the uncoated tools. This result indicated that the bi-layer (SiC+diamond) coated tools exhibited better cutting performance than the uncoated tools. Thus, SiC interlayers were demonstrated as a suitable option for adherent diamond coatings on the cemented carbide components and cutting tools. © 2014 Elsevier B.V.


Hei H.,Taiyuan University of Technology | Yu S.,Taiyuan University of Technology | Shen Y.,Taiyuan University of Technology | Li X.,The Ningbo Branch of Ordnance Science Institute of China | And 3 more authors.
Surface and Coatings Technology | Year: 2015

Cubic silicon carbide (β-SiC) thin films were synthesized on cemented carbide (WC-Co) substrates as an interlayer for modifying the adhesion of diamond coatings. The influence of varying the hydrogen (H2)/tetramethylsilane (TMS) flow ratios on the microstructure, phase composition and adhesion of the β-SiC films was investigated. It was found that with the increase of the H2/TMS flow ratios, the SiC crystallite size increases from 6.5nm to 22.2nm. When the flow ratio was 40:5, the film was formed of loose cauliflower-like agglomerates, containing SiC granular particles. With the flow ratio increased from 40:5 to 120:5, the films became more uniform and denser, resulting in adhesion enhancement. However, when the ratio increased from 160:5 to 200:5, clusters composed of faceted particles replaced the agglomerates, and the adhesion reduced. The β-SiC film deposited with a H2/TMS flow ratio of 120:5 possessed a more uniform and denser structure, as well as better adhesion than the others. After subsequent diamond deposition, homogeneous nanocrystalline diamond coatings were realized on the β-SiC interlayered substrates. Compared with the results on the well-known two-step chemically etched substrates, the diamond coatings deposited on the substrates with the β-SiC interlayer possess excellent adhesion. It was also validated in this research that the β-SiC interlayer deposited with a H2/TMS flow ratio of 120:5 was effective in enhancing the adhesion of diamond coatings prepared on WC-Co substrates. © 2015 Elsevier B.V.


Zhang X.,The Ningbo Branch of Ordnance Science institute of China | Ren Z.,The Ningbo Branch of Ordnance Science institute of China | Zhu X.R.,The Ningbo Branch of Ordnance Science institute of China | Ren J.,The Ningbo Branch of Ordnance Science institute of China | And 2 more authors.
Advanced Materials Research | Year: 2014

The behavior of flow stress of Al-Mn alloy during hot compression at the condition of ε=0.05,0.5,5,25s-1 while the temperature range from 300°C to 450°C was studied by Gleblee-3500. The results show that the Al-Mn alloy possess the remarkable characteristic of a peak stress, followed by a steady-state flow stress when deformed in the temperature range from 300°C to 450°C with a strain rates range from 0.05s-1 to 0.5s-1 ·When the strain rate is higher than 5s-1 dynamic recrystallization will happen. The true stress decrease with increasing compression temperature and increases with the increasing strain rate. A constitution equation which can describe the relationship of ε,T and σ is achieved. Also the activation energy for deformation is calculated. © (2014) Trans Tech Publications, Switzerland.


Li X.,Central South University | Song Y.,Central South University | Ni P.,The Ningbo Branch of Ordnance Science Institute of China | Liu F.,Central South University
Jinshu Xuebao/Acta Metallurgica Sinica | Year: 2015

To solve such problems as sensitivity to noise and low accuracy of grain size evaluation using traditional ultrasonic time-domain attenuation method, an ultrasonic nondestructive evaluation model based on multiscale attenuation coefficient was proposed. The distribution of time-scale of ultrasonic energy was obtained by means of wavelet transformation, then to calculate the distribution of attenuation coefficient with scale, and to make a comprehensive analysis of attenuation characteristics of various scales. After the weighted multi-scale ultrasonic attenuation coefficient was defined, a multi-scale ultrasonic attenuation evaluation model was established on the basis of combination of optimal dimension and normalized weight distribution strategy designed by particle swarm optimization. 304 stainless steel was used in the test. The distribution of attenuation coefficient with scale shows that ultrasonic wave of small scales attenuates fast, presenting the frequency characteristics of ultrasonic attenuation among high scattering materials. Following increase of the sample grain size, ultrasonic attenuation of all scales was intensified significantly. Test results show that the sound velocity method, the traditional evaluation method and the proposed method have maximum systematic errors of +12.57%, +5.85% and -1.33%, respectively. With these 3 methods, evaluation results of the sample with a mean grain size of 103.5 μm measured by metallographic method are (110.4±7.8), (98.2±6.6) and (101.7±3.9) μm, respectively, showing that the presented method can not only reduce the systemic error, but also can effectively control the random error by constant Q filtering properties of wavelet transformation. This model can be extended to grain size evaluation of other metals. © Copyright.


Zhang Y.,Zhejiang University | Wang Z.,The Ningbo Branch of Ordnance Science Institute of China | Zhao Y.,Zhejiang University
Indian Journal of Engineering and Materials Sciences | Year: 2014

ZnO micro-crystals are prepared by hydrothermal reaction using PEG-20000/cyclohexane as additive, and Zn(OH)4 2- and Zn(NH3)4 2+ as precursors. Characterizations of the ZnO samples are conducted with X-ray diffraction (XRD), scanning electron microscopy (SEM) and selected area electron diffraction (SAED). The results show that the synthesized crystals belong to hexagonal crystalline system with typical morphology of ZnO aggregates composed of nano rod-like monocrystals which grew into various morphologies such as robust, tapered and clustered under different reaction conditions. The aggregates could be assembled with a controllable size of 2~4 μm. In the aid of PEG-20000, the specific face of crystal formed nucleus preferentially and then grew directionally. In addition, the tests of the microwave electromagnetic performance show a significant effect of the crystal morphology on the dielectric loss of ZnO. With the higher polar growing ability, the faster velocity, the shorter growing period and the more lattice defects, the polarization would become more intense to cause more dielectric loss of ZnO consequently.


Li X.-J.,The Ningbo branch of Ordnance Science institute of China | Gao Y.-L.,The Ningbo branch of Ordnance Science institute of China | Yin Y.,Ningbo Yinzhou vocational education center school | Zheng S.-Q.,The Ningbo branch of Ordnance Science institute of China | Zheng Y.-S.,The Ningbo branch of Ordnance Science institute of China
Materials Science Forum | Year: 2016

Numerical simulation method was developed to investigate the performance of plasma and multi-physical fields in direct current (DC)arc plasma reactor for chemical vapor deposition (CVD) Diamond film, in order to obtain more information on the process of CVD. Finite Volume Method (FVM) was adopted. Continuous arc forming and the dynamic formation process of rotating arc plasma were shown in this paper. Multi-physics field in deposition chamber were modeled including flow field, temperature field. Distribution of velocity and temperature were obtained by solving momentum and energy equation with SIMPLE separation algorithm. Simulation results show that, plasma temperature near the cathode tip is the highest, which is more than 1×104K. The plasma distribution shape like the bell jar. The changing regularity of outlet velocity, temperature and static pressure with the distance from the anode center were revealed. The effectiveness of plasma temperature and gas flow calculated was confirmed by the experimental results. The research results provide the theoretical foundation for obtaining uniform diamond thick film. © 2016 Trans Tech Publications, Switzerland.


Hu H.-W.,Changsha University of Science and Technology | Li X.-B.,Central South University | Yang Y.,Central South University | Ni P.-J.,The Ningbo Branch of Ordnance Science Institute of China | Tong L.-J.,Central South University
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2012

An automatic method of inspecting porosity in CFRP (Carbon fiber reinforced plastic) with complex surface by ultrasonic was presented. Through-transmission mode was used to obtain ultrasonic signals of CFRP test blocks with given porosity, and phase-unwrapping method was used to calculate the test blocks phase velocity, and an ultrasonic inspection model based on the relation between phase velocity and porosity was established. The 3D surface data of CFRP with complex surface were obtained by ultrasonic measurement, and then the inspection path was planned after the CAD model had been reconstructed. A multi-degree-of-freedom manipulator was used to acquire ultrasonic signals of CFRP with complex surface, and its porosity was calculated according to the ultrasonic inspection model presented. In order to verify the validity of the presented method, microphotography was used to get the porosity of CFRP with complex surface after block slitting and polishing. The results show that the porosity inspected by the ultrasonic method is in good agreement with that obtained by microphotography.

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