Papers by Keyword: Layered Composite

Abstract: Based on taking combustion synthesis into high-gravity field to fabricate high-hardness bulk solidified TiC-TiB₂ composite, layered composite of solidified TiC-TiB₂ ceramic to Ti-6Al-4V alloy was obtained by the introduction of Ti-6Al-4V alloy plates at the bottom of graphite crucible. XRD, FESEM and EDS results showed that the layered composite was achieved in multi-scale (micron/submicron/micro-nanometer) and multi-level (TiC_1-x-TiB-TiB₂ + TiB₂-Ti-TiC_1-x-TiB + TiB₂-TiC_1-x-TiB-Ti + TiB-TiC_1-x-Ti + TiC_1-x-Ti + Ti) graded microstructure between the ceramic and Ti alloy, which was characterized by size and distribution of TiB₂ and TiB, thereby paving a new way for developing light-weight materials for special engineering.

Abstract: This paper changed the matrix structure model of traditional electrode materials from the the composition of the internal structure of the matrix, used solid-solid compound method of hot pressing diffusion welding for sandwich type structure Ti-Al layered composite materials, The Ti/IrO2-Ta2O5 were got by typical oxygen evolution model coating ingredient(mole ratio of Ir to Ta was 7:3). Microstructure of the layered composite materials was studied by scanning electron microscope (SEM) and Energy Dispersive Spectrometer (EDS), and then the current distribution performance as the anode material for nickel electrowinning in NiSO4-H2SO4 system was characterized by electric analysis module of ANSYS program . The results showed that, The findings indicate that the interface formation of Ti-Al layered composite materials was a reaction-diffusion process. In the technology conditions of this subject, the phase of interface was Al3Ti. Compared with the traditional DSA (Dimensionally Stable Anode) titanium anode, the Ti-Al layered composite anode showed a more uniform current distribution performance.

Abstract: Ballistic impacting test has been conducted on laminated SiC/Al-Cu composite with three layers ceramic plates and metal multi-constrain, while the target sample was prepared through squeeze casting. The ballistic testing result showed that composite exhibited good structural integrity. Mass loss and length loss of projectile are 63.65% and 65.43% respectively, mainly resulted from abrasion of crushed ceramic particles and melting erosion itself. Multi-constrain of metal ensured to maximize the role of abrasion of crushed ceramic powder, in addition, the heat generated at instantaneous projectile-target contact led to partial corrosion on projectile. Subject to ballistic impacting, SiC ceramic was transgranularly fractured and crushed, metal lining was melt, deformed and destroyed, as well as the interface dissociation happened between ceramic and metal. These processes absorbed great kinetic energy of projectile, so as to stop the penetration of incident mass within the laminated structure. Layered composite failure was completed under synergistic effect of three fracture modes, including ceramic brittle fracture, interface debonding and metal fracture.

Abstract: Layered hydroxyapatite (HA) based ceramic composites consisting of a strong ceramic composite core, 3 mol% yttrium stabilized zirconia (3Y-TZP) with 30 or 40 vol% HA, and a HA-rich porous coating were fabricated using a coating deposition and co-sintering process in the present study. The aim is to develop HA-based bio-ceramic composites that retain the bio-compatibility of HA and the preferred scaffold structure, but have much improved structural properties required for implants. Two different coating techniques, sol-gel derive HA coating and HA solution coating, have been used to deposit the HA coating on the strong HA-containing 3Y-TZP core, which has been pre-sintered at 900°C and has a green-machined surface finish. The upper limit for the final sintering of the layered ceramic composites is set at 1,350°C based on the individual sintering properties of HA and 3Y-TZP. SEM observations have been conducted on the coating surface, sectioned surface of coating and substrate/core to characterize the microstructures of coating and substrate and their interface. Preliminary mechanical tests and XRD tests are also performed to characterise the structural properties at different temperatures.

Abstract: Mo-Ti₃SiC₂ layered composite was successfully prepared by spark plasma sintering at 1573 K for 20 min under a pressure of 50 MPa in vacuum. The Mo and Ti₃SiC₂ layers were metallurgically bound together without noticeable superficial defects and micro-cracks at the interface. The fabricated Mo-Ti₃SiC₂ layered composite was annealed at 1273 K under vacuum for 5, 10, 20 and 40 h to study the composite’s thermal stability. Three intermediate layers, Mo₂C, MoSi₂ and Ti₅Si₃C_x, were formed at the interface. Experimental results showed that the Mo-Ti₃SiC₂ layered composite prepared in this study has good interfacial stability at elevated temperature.

Abstract: Taking Sn as the third element in the Al/Pb immiscible system, the Al-Sn-Pb layered composite materials at different temperatures were prepared by solid-liquid coating method. Microstructure of the layered composite materials was studied by scanning electron microscope (SEM) and Energy Dispersive Spectrometer (EDS), and then the flexural strength and interface adhesion of the layered composite materials were measured. The results showed that, introducing of Sn reduced the enthalpy heat of mixing of Al/Pb system to be negative, and inter-diffusion of elements in the interface region occurred, and a metallurgical bonding interface between Pb and Al formed. The optimum diffusion-sintering temperature-time for the best flexural strength were determined by 250^οС , 0.5h, respectively. Under the controlled conditions, the mechanism was discussed.

Abstract: We proposed using Ti-Al and Ti-Cu laminated composites instead of single Ti electrode metals, as well as studied the difference in performance between laminated composite electrode materials and pure-Ti electrode. The analysis of the conductivity and electrochemical performance of electrode matrix material indicates the result that the improvement of matrix material by using Ti-Al and Ti-Cu laminated composites, better performance for conductivity of electrode, and be beneficial to homogenize the electrode surface potential and current distribution and promote electrocatalytic activity between polar plates. Whereas comparison between Ti-Al and Ti-Cu laminated composites, Ti-Cu laminated composites is better in performance.

Abstract: In this paper, continuous running test was conducted using the disk drive spindle micromotors used in automobiles DVD. The commutator and brush were made of AuAg/AgCuNiCe/Cu and AgPd/CuNiSn layered composite respectively. In order to investigate the wear behavior of the commutator, the micromotors were dissected after ran continuously for different time. The worn surface of the commutator and the brush were characterized using an SEM equipped with EDS. Also, the cross section of the commutator was analyzed. It was shown that the AuAg layer was not totally worn off until 1500 h of running test. AuAg transferred from the commutator to the brush. It was interesting that Au was found on the silver layer where the depth of wear crater surpassed the thickness of the original AuAg layer. Small particles enriched in Cu, Ni and Ce were observed on the contact surface of AgCuNiCe layer, which was thought to improve the wear resistance of the commutator. The wear mechanism was mainly slight abrasion whereas no effect of arc was found on the sliding contact area.

Abstract: Residual strain profiles were measured by synchrotron X-ray radiation in Al2O3/Y-stabilized ZrO2 (YSZ) ceramic laminates. Different stacking sequences were employed, including alternating layers containing 5 and 40 vol.% YSZ. Residual strains were found to be fairly constant within each layer; although they change at the interface between layers with different compositions. Different behaviour is observed for the strains along the in-plane and normal directions.

Abstract: Mo-Ti3SiC2 layered material was prepared by spark plasma sintering. Mixed Ti, Si, graphite and Al powder with molar ratio of 3Ti:1Si:2C:0.2Al was put into a graphite mould and pressed with a pressure of about 0.5 MPa, then, Mo powder was put on top of the mixed powder. Experimental results showed that Mo-Ti3SiC2 layered material could be fabricated successfully by sintering the above powder mixture at 1300°C for 20 minutes under a pressure of 50 MPa in vacuum. The surface and interfaces of the layered composite were tight and clear without any observable crack. In order to study the thermal stability at elevated temperature, the fabricated Mo-Ti3SiC2 layered composite was heat treated at 800°C for 5, 10, 20 and 40 hours. After 40 hours of annealing, the intermediate layers formed between the Mo and Ti3SiC2 matrix grew thicker. The interfaces are clean and tight with no obvious formation of voids and new phases. The initial 10 hours of annealing is the fast growing period, after that, the growth rate slowed down significantly.