• Journal of Welding and Joining
• /
• 제18권5호
• /
• pp.105-111
• /
• 2000

The wear behavior of thermal sprayed AlSiMg-40TiC composite coatings were studied as a function of load and sliding velocity under unlubricated conditions. Experiments were performed using a block-on-ring(WC-6wt%/Co, Hv 1500) type. The tests were carried out a various load(30∼ 125.5N) and sliding velocity(0.5∼2.0m/s). Three wear rate regions were observed in the AlSiMg-40TiC composite coatings. The wear rate in region I at low load (less then 8N( were less than 1×{TEX}$10^{-5}${/TEX}㎣/m. Low wear rates in region I resulted from the load-bearing capacity of TiC particles. The transition from region I to II occurred when the applied load exceeded the fracture and pull-out strength of the particles. The TiC fractured particles trapped between the specimen and the counterface acted as third-body abrasive wear. The subsurface layer worn surface in region II was composed of the mechanically mixed layer (MML). The wear rate increase abruptly above a critical load (region III). The high wear rate in region III was induced by frictional temperature and involves massive surface damage.

• 대한금속재료학회지
• /
• 제56권12호
• /
• pp.854-860
• /
• 2018

In spite of the many attractive properties of (W,Ti)C, its low fracture toughness limits its wide application. To improve the fracture toughness generally a second phase is added to fabricate a nanostructured composite. In this regard, graphene was considered as the reinforcing agent of (W,Ti)C. (W,Ti)C-graphene composites that were sintered within 2 min using pulsed current activated heating under a pressure of 80 MPa. The rapid consolidation method allowed retention of the nano-scale microstructure by blocking the grain growth. The effect of graphene on the hardness and microstructure of the (W,Ti)C-graphene composite was studied using a Vickers hardness tester and FE-SEM. The grain size of (W,Ti)C was reduced remarkably by the addition of graphene. Furthermore, the hardness decreased and the fracture toughness improved with the addition of graphene.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 하계학술대회 논문집
• /
• pp.71-74
• /
• 2000

Pt/Pb$TiO_3$/$SrTiO_3$/p-Si films were prepared by metallo-organic solution deposition(M0SD) method and investigated its structure and ferroelectric properties. Crystallinity of specimen as a funtions of post annealing temperature and the thickness of $SrTiO_3$(STO) buffer layer was studied using XRD and AFM. Based on C-V and P-E curve, $PbTiO_3$(PTO) capacitors showed good ferroelectric hysteresis arising from the polarization switching properties. When the thickness of ST0 buffer layer between PTO and Si substrate was 260 nrn and the post annealing temperature was $650^{\circ}C$, it was showed that production of the pyrochlore phase due to interdiffusion of Si into FTO was prevented. The dielectric constant of FTO thin films calculated from a maximum Cma in the accumulation region was 180 and the dielectric loss was 0.30 at 100 kHz frequency. The memory window in the C-V curve is 1.6V at a gate voltage of 5V.

• 한국재료학회지
• /
• 제18권10호
• /
• pp.558-563
• /
• 2008

TiAlN films were deposited on WC-5Co substrates with different buffer layers by D.C. magnetron sputtering. The films were evaluated by microstructural observations and measuring of preferred orientation, hardness value, and adhesion force. As a process variable, various buffer layers were used such as TiAlN single layer, TiAlN/TiAl, TiAlN/TiN and TiAlN/CrN. TiAlN coating layer showed columnar structures which grew up at a right angle to the substrates. The thickness of the TiAlN coating layer was about $1.8{\mu}m$, which was formed for 200 minutes at $300^{\circ}$. XRD analysis showed that the preferred orientation of TiAlN layer with TiN buffer layer was (111) and (200), and the specimens of TiAlN/TiAl, TiAlN/CrN, TiAlN single layer have preferred orientation of (111), respectively. TiAlN single layer and TiAlN/TiAl showed good adhesion properties, showing an over 80N adhesion force, while TiAlN/TiN film showed approximately 13N and the TiAlN/CrN was the worst case, in which the layer was destroyed because of high internal residual stress. The value of micro vickers hardness of the TiAlN single layer, TiAlN/TiAl and TiAlN/TiN layers were 2711, 2548 and 2461 Hv, respectively.

• 한국윤활학회:학술대회논문집
• /
• 한국윤활학회 2004년도 학술대회지
• /
• pp.41-46
• /
• 2004

This study deals with the friction and wear characteristics of C-N coated spur gear. The PSII apparatus was built and a SCM415 test piece and test gear with steel substrate was treated with carbon nitrogen by this apparatus. The composition and structure of the surface layer were analyzed and compared with that of PVD coated TiN layer. It was found that both of friction coefficients of C-N coating and TiN coaling decreased with increasing load, however, C-N coating showed relatively lower friction coefficient than that of TiN coating. We was investigated the effect of C-N coating on hardness, friction and wear. The TiN coated gear showed more serious friction phenomena than that of C-N coated gear. It was considered that coating of TiN, which was conducted at a vacuum chamber at about $500^{\circ}C$ results in a tempering of base material that causes microstructure change, which in turn resulted in decreasing of hardness. The C-N coated gear and pinion had higher wear resistance that of TiN coated gear and pinion. C-N coating significantly improved the friction and wear resistance of the gear.

• 한국재료학회지
• /
• 제12권10호
• /
• pp.825-830
• /
• 2002

The growth rate of solid grains in TiC-XC-2vol% and TiC-XC-30vo1% Ni cermets, where X=Zr, W or Mo, was fitted to an equation of the form $d^3$-$do^3$=Kt. The grain growth behavior during liquid phase sintering at 1673K decreased markedly with addition of $Mo_2$C or WC and increased with addition of ZrC. The contiguity ratio was greater in the alloys with smaller growth rate constant and decreased with increasing Ni content in the $TiC-Mo_2$C-Ni cermet. The grain growth mechanism could be explained by the effect of contiguous grain boundaries in restricting the overall grain growth.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제51권4호
• /
• pp.141-146
• /
• 2002

The mechanical and electrical properties of the pressureless sintered SiC-TiB$_2$electroconductive ceramic composites were investigated as functions of the transition metal of TiB$_2$. The result of phase analysis for the SiC-TiB$_2$ composites by XRD revealed $\alpha$-SiC(6H), TiB$_2$, and YAG(Al$_{5}$Y$_3$O$_{12}$) crystal phases. The relative density showed the lowest 84.8% for the SiC-TiB$_2$composites added with 39vol.%TiB$_2$. Owing to crack deflection, crack bridging and YAG of fracture toughness mechanism, the fracture toughness showed the highest value of 7.8 MPa.m$^{1}$2/ for composites added with 39vol.%TiB$_2$under a pressureless annealing at room temperature. The electrical resistivity of the SiC-27vol.%TiB$_2$ composites was negative temperature coefficient resistance(NTCR), and the electrical resistivity of the besides SiC-27vol.%TiB$_2$composites was all positive temperature coefficient resistance(PCTR) in the temperature range of $25^{\circ}C$ to $700^{\circ}C$.EX>.

• 한국세라믹학회지
• /
• 제53권4호
• /
• pp.393-399
• /
• 2016

We have successfully fabricated 3D (3-dimensional) nanostructures of $TiO_2$ coated with a $g-C_3N_4$ layer via hydrothermal and sintering methods to enhance photoelectrochemical (PEC) performance. Due to the coupling of $TiO_2$ and $g-C_3N_4$, the nanostructures exhibited good performance as the higher conduction band of $g-C_3N_4$, which can be combined with $TiO_2$. To fabricate 3D nanostructures of $g-C_3N_4/TiO_2$, $TiO_2$ was first grown as a double layer structure on FTO (Fluorine-doped tin oxide) substrate at $150^{\circ}C$ for 3 h. After this, the $g-C_3N_4$ layer was coated on the $TiO_2$ film at $520^{\circ}C$ for 4 h. As-prepared samples were varied according to loading of melamine powder, with values of loading of 0.25 g, 0.5 g, 0.75 g, and 1 g. From SEM and TEM analysis, it was possible to clearly observe the 3D sample morphologies. From the PEC measurement, 0.5 g of $g-C_3N_4/TiO_2$ film was found to exhibit the highest current density of $0.12mA/cm^2$, along with a long-term stability of 5 h. Compared to the pristine $TiO_2$, and to the 0.25 g, 0.75 g, and 1 g $g-C_3N_4/TiO_2$ films, the 0.5 g of $g-C_3N_4/TiO_2$ sample was coated with a thin $g-C_3N_4$ layer that caused separation of the electrons and the holes; this led to a decreasing recombination. This unique structure can be used in photoelectrochemical applications.

• 한국세라믹학회지
• /
• 제36권1호
• /
• pp.7-14
• /
• 1999

SHS 마이크로파를 이용하여 티타늄, 지르코니움과 보론분말을 혼합하여 TiZrB2 고용체를 합성된 분말의 분말특성과 소결체의 소결특성을 연구하였다. 합성 중 온도 profile 결과 연소온도와 연소속도는 Zr의 몰비가 증가함에 따라 증가 하였으며, Ti0.2Zr0.8B2조서에서 연소온도와 연소속도는 285$0^{\circ}C$, 14.6m/sec로 최고값을 얻었다. 190$0^{\circ}C$에서 30 MPa의 압력으로 60분간 고온가압소결한 TiZrB2고용체는 TiB2와 ZrB2로 상분리가 최고값을 얻었다. 190$0^{\circ}C$에서 30MPa의 압력으로 60분간 고압가압소결한 TiZrB2 고용체는 TiB2와 ZrB2로 상분리가 일어나 복합체가 형성되었으며, Ti0.8Zr0.2B2에서 가장 좋은 물성값을 나타내었는데 상대밀도, 꺽임강도, 파괴인성 및 경도는 각각 99%, 680MPa, 7.3MPam1/2, 2750Kg/$ extrm{mm}^2$이었다.

• 한국분말재료학회지
• /
• 제5권4호
• /
• pp.286-292
• /
• 1998

Ni$_3$Al intermetallic compound has been tested as a binder phase, in order to improve the oxidation resistance and the mechanical properties of TiC-Ni cermet at a high temperature. The wettability of $Ni_3Al$ on TiC and the optimum sintering condition were investigated in TiC-(30, 40) vol% $Ni_3Al$ cermets with the sintering temperature (1380~$1430^{\circ}C$) and time (30~99 min). The results are summarized as follows: 1) Ni$_3$Al showed good wettability on TiC above 1400$^{\circ}C$ ; 2) The shrinkages of the specimens increased with the sintering temperature, the sintering time and the binder content, whereas the relative densities were decreased; 3) Any other phase did not appeared in the microstructures of all sintered cermets. The grain sizes of TiC became larger as the sintering temperature and the sintering time as well as the binder content increased; 4) The hardness of the cermets decreased with increase in the sintering temperature and the sintering time as well as the binder content; 5) The transverse-rupture strength of the cermets increased with the sintering temperature and the sintering time, whereas it decreased with the binder content.