• Title/Summary/Keyword: carbonitride

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Improvement of the mechanical properties of titanium carbonitride-metal composites by modification of interfaces (계면 개선을 통한 타이타늄 탄/질화물 금속 복합재료의 기계적 물성 향상)

  • Kwon, Hanjung
    • Ceramist
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    • v.23 no.2
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    • pp.114-131
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    • 2020
  • Fracture in the titanium carbonitride-metal composites occurs by crack propagation through the carbonitride grains or in the interfaces. Thus, intrinsic properties of the carbonitride need to be enhanced and the interfaces should be also modified to coherent structure to strengthen the composites. Especially, interfacial structure can be the main factor to determine the mechanical properties of titanium carbonitride-metal composites because the interfaces between carbonitride grains and metallic phase are weak parts due to heterogeneous nature of carbonitride and metallic phase. In this paper, methodologies for improving the interfacial structure of titanium carbonitride-metal composites are suggested. Total area of the interfaces can be reduced using solid solution type carbonitrides as raw materials instead of a mixture of various carbonitrides in the composites. Also, synthesis of titanium carbonitride-metal composite powders and the low-temperature sintering of the composite powders for short time can be the way for formation of coherent interfaces. The sintering of the composite powders for short time at low temperature can reduce the potential of formation of interfaces by dissolution and precipitation of carbonitride in the liquid metal. As a result of formation of coherent boundaries due to low-temperature and short-time sintering, interfaces between titanium carbonitride grains and metallic phase have the favorable structure for the enhanced fracture toughness. It is believed that the low-temperature sintering of solid solution type composite powders for short time can be the way to improve the low toughness of the titanium carbonitride-metal composites.

Synthesis and Magnetic Characterization of Fe-nitride for Magnetic Recording (기록매체용 Iron-nitride의 합성 및 자기특성)

  • O, Yeong-U;Kim, Mun-Seop
    • Journal of the Korean Magnetics Society
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    • v.2 no.3
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    • pp.244-250
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    • 1992
  • Iron nitride $Fe_4N$ by partial substitution of nitrogen by carbon was prepared by nitriding the iron oxalate whose thermal decomposition gives a carburating atmosphere. Iron oxalates, the precursors, were prepared by precipitation and co-precipitation. The size and shape of the carbonitride particles could be controlled by modifying the conditions of preparation of the oxalate precursor. From the results of electron micrographs, it is clear that the $Fe_4N$ pigment particle maintains the original shape(needle shape) of the starting materials and that it consists of fine unit particles which link together to form a stereo-network structure. An investigation of the $Fe^{II}_3\;Fe^I_{1-x}\;Sn_xN_{1-y}C_y$ solid solution has shown that Sn plays the role of a growth inhibitor of the elementary microcrystallites of the iron carbonitride. The coercive force and saturation magnetization of iron carbonitride obtained from co-precipitated iron oxalate were 500 Oe and 120 emu/g, respectively.

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Effect of Graphite Additions on the Properties of $Ti(C_xN_{1-x})$ Ceramics (Graphite 첨가에 따른 $Ti(C_xN_{1-x})$세라믹스의 물성)

  • Ko, Jun;Choi, Young-Min;Lee, Jae-Do;Kim, Chong-Oh
    • Journal of the Korean Ceramic Society
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    • v.34 no.5
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    • pp.443-448
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    • 1997
  • Titanium carbonitride (Ti(CxN1-x)) ceramics were prepared by hot pressing of the mixture of TiN and graphite. Hot pressing was performed in a graphite mold at 198$0^{\circ}C$ for 40 min under 44 MPa in N2 atmosphere. The effect of graphite addition on sinterability and the mechanical properties of titanium carbonitride were investigated. In this study, the solubility limit of graphite in Ti(CxN1-x) was slightly below 10 wt% based on the results of XRD analysis. Within the solubility limit, graphite dissolved completely into titanium nitride and formed the single phase Ti(CxN1-x) solid solution. Peak relative density of 99% and hardness of 16 GPa were observed for Ti(CxN1-x) ceramics with 7 wt% graphite while maximum flexural strength of 500 MPa and fracture toughness of 4.0 MPa.m1/2 were observed for Ti(CxN1-x) ceramics with 10 wt% graphite. The electrical resistivities of the ceramics with 7 wt% and 10 wt% graphite were observed 40 {{{{ mu OMEGA }}cm and 50 {{{{ mu OMEGA }}cm respectively.

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Mechanical Properties and Cutting Performance of Ti(CN) Based Carbonitride Ceramics (Ti(CN)기 탄화물질 세라믹스의 기계적 특성과 절삭성능)

  • Park, Dong-Su;Lee, Yang-Du;Jeong, Tae-Ju;Gang, Sin-Hu
    • 연구논문집
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    • s.28
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    • pp.193-207
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    • 1998
  • Fully dense THCN) based carbonitride ceramics were fabricated by pressureless sintering. During sintering, solid solutions were formed from the ceramic ingredients. The ceramics exhibited microvickers hardness of 1560-2050kgf/mm2, fracture toughness of 3.0-5.4 MPa $m^(1/2)$, and three point flexural strength of 645-1072 MPa. Some of the ceramics were shaped in a cutting tool, and the cutting performance was evaluated. In case of cutting SCM440 alloy steel, the ceramics showed better performance than the commercially available alumina-titanium carbide ceramic cutting tool. Considering the excellent productivity of pressureless sintering compared with other densification methods and their cutting performance, this new class of ceramics are very promising for wear resistant applications.

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A Study on the Synthesis of Titanium Carbonitride by SHS(Self-propagating High-temperature Synthesis) Method (자체반응열 고온합성법을 이용한 Titanium Carbonitride의 합성에 관한 연구)

  • Ha, Ho;Hwang, Gyu-Min;Lee, Hee-Cheol
    • Journal of the Korean Ceramic Society
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    • v.31 no.6
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    • pp.637-642
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    • 1994
  • Using SHS(Self-propagating High-temperature Synthesis) method, the optimum synthetic condition of titanium carbonitride was established by controlling the parameters such as relative density of mixture (Ti+C), nitrogen pressure, additive amounts of titanium hydride(TiH1.924) and protecting heat loss. Under 1 atm nitrogen pressure, nitridation ratio with changing relative density of the sample compacts has a maximum (87.2%) at about 55%, and in the case of enveloping the pellet with a quartz tube, the highest nitridation ratio of 90% was obtained at about 68%. At relative density of 55%, nitridation ratio with the nitrogen pressure has a miximum (87.3%) at 7 atm. As the amounts of additive titanium hydride increased, nitridation ratio decreased at below 7 atm nitrogen pressure and, increased at above this pressure until percent of addition percent reached 15 wt% and decreased abruptly upon futher increases in titanium hydride. In the synthesis of TiCxNy by combustion reaction, heat transfer from combustion zone to preheating zone and nitrogen gas penetration into the compact were found to be important factors affecting the TiCxNy formation. It was difficult to obtain high nitridation ratio when the conbustion temperature was either too high or too low, and it seems that the retention of high temperature after a combustion wave sweeped through the reactant mixture pellet is critical to obtain a satisfactory nitridation ratio.

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A Study on Heating Element Properties of Carbon Nanotube/Silicon Carbonitride Composite Sheet using Branched Structured Polysilazane as Precursor (가지 달린 구조의 폴리실라잔을 전구체로 이용해 제조한 카본 나노튜브/실리콘 카보나이트라이드 복합체 시트의 발열특성에 관한 연구)

  • Huh, Tae-Hwan;Song, Hyeon Jun;Jeong, Yeong Jin;Kwark, Young-Je
    • Composites Research
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    • v.33 no.6
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    • pp.395-400
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    • 2020
  • In this paper, we manufactured silsesquiaznae (SSQZ)-coated carbon nanotube (CNT) surface heating elements, which allowed stable heating at high temperatures. The prepared composite sheet was confirmed by FE-SEM that the SSQZ fully coated the surface of CNT sheet. Furthermore, it was also confirmed that the silicon carbonitride (SiCN) ceramic formed by heat treatment of 800℃ have no defects found and maintain intact structure. The CNT/SiCN composite sheet was able to achieve higher thermal stability than raw CNT sheets in both nitrogen and air atmosphere. Finally, the CNT/SiCN composite sheet was possible to heat up at a temperature of over 700℃ in the atmosphere, and the re-heating was successfully operated after cooling.

Nb-carbonitride Analysis Techniques in Nb-steels (강 중 Nb계 탄질화 석출물 정량분석 기술)

  • Lee, J.J.;Jung, S.W.;Yoo, K.S.
    • Analytical Science and Technology
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    • v.7 no.4
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    • pp.493-504
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    • 1994
  • The morphology and structure of precipitates of formed in Nb steels were investigated using SEM, TEM and XRD. The quantitative analysis of the precipitates was performed by ICP-AES. The potentiostatic etching method was employed as an extraction method using 10% AA-methanol and 15% Na-citrate electrolytes. The two selected potentials relative to SCE(Standard Calomel Electrode), -100mV in 10% AA-methanol solution and -250mV in 15% Na-citrate solution were found to be effective for the extraction. XRD analysis showed that composition of Nb carbonitride in Nb-steel(0.01% C-0.7% Nb-0.004N) was $NbC_{0.65}N_{0.2}$.

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