• 한국표면공학회지
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• 제31권3호
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• pp.157-164
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• 1998

Effects of alloying elements on the pitting behavior of Ti-Al intermetalic compounds in the electrolytic soution containing Cl- were investigated through electrochemical tets and corrosion morphologies. Corrosion potential increased in the case of Cr addition to Ti-48%Al, whereas it decreased in the case of Si and B addition. The simultaneous addition of Cr and Si increased passive current density and decrosion corrosion potential. The passive current density of N addtion was higher than that of B addition in H2SO4 solution. With the addition of alloying elements, The pitting resistance decreased in order of TiAl>TiAlSi>TiAlN>TiAlB>TiAlCr and whin siumultaneous addition, it decreased in order of TiAlCrSi>TiAlCrBN>TiAlCrrN. The surface merohology after pitting test showed that the TiAl coataining Si had for fewer pits than that containing Cr and N simultaneously.

• 한국재료학회지
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• 제9권9호
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• pp.900-904
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• 1999

TiO$_2$분말을 $Al_2$O$_3$분말에 대하여 무게비로 1,3,5,7,9와 11wt%로 혼합하여 알루미나 세라믹스의 미세조직 및 기계적 물성변화를 관찰하였다. TiO$_2$분말의 첨가량이 증가할수록 부피비중은 3.26에서 2.90g/㎤으로 감소하였으며 기공율은 TiO$_2$분말의 첨가량이 7wt%까지는 감소하였으나 9wt%이상 첨가할 경우 증가하였다. 압축강도 측정 결과 파괴강도는 TiO$_2$분말의 첨가량이 7wt%까지는 증가하였으나 9wt%이상 첨가할 경우 감소하였다. 3점 곡강도를 측정한 결과 최대 파괴 응력 값은 TiO$_2$분말의 첨가량이 증가할수록 감소하였다.

• 한국세라믹학회지
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• 제33권9호
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• pp.1038-1044
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• 1996

The variations of sintering and electrical characteristics of semiconducting BaTiO3 ceramics with sintering agents added were investigated comparing the case of BaB2O4 addition to BN and TiO2 addition. When BaB2O4 added in BaTiO3 ceramics the densitifcation of specimen could be acheived more easily and recvealed the better PTCR characteristics than BN and TiO2 addition. As increase of addition of BaB2O4 in BaTiO3 spec imens the slope of resistivity jump also increased but the temperature of maximum resistivity decreased, It was supposed that addition of BaB2O4 led to increase of Ns (acceptor state density) value at grain boundaries.

• Journal of Welding and Joining
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• 제26권1호
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• pp.76-82
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• 2008

The effect of Nb addition on the precipitation and precipitate coarsening behavior was investigated in Ti and Ti + Nb steel weld HAZ. A dilatometer equipped with a He-quenching system was used to simulate the weld thermal cycle. Compared to $TiC_yN_{1-y}$ precipitate in a Ti containing steel, $Ti_xNb_{1-x}C_yN_{1-y}$ complex particle with addition of Nb is precipitated in a Ti + Nb containing steel. Meanwhile, precipitate coarsening occurred more easily in Ti + Nb steel, which may be because the high temperature stability of $Ti_xNb_{1-x}C_yN_{1-y}$ complex particle is deteriorated by the Nb addition.

• 한국세라믹학회지
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• 제35권12호
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• pp.1316-1322
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• 1998

The amount of VC and C/N ratio in Ti(CN) was varied to investigate the effect of VC addition on the mi-crostructural change in Ti(CN)-Ni system. As the amount of VC addition increases in Ti(C0.7N0.3)-20Ni sys-tem a complete solid solution was observed in Ti(C0.7N0.3)-20Ni-25VC system. It implies that the ratio of the dissolution rates of Ti(C0.7N0.3)to that of VC is nearly 2:1 at the sintering conditions used in this study. It was found from the experiments that the system composed of the Ti(C0.7N0.3) phase exhibits a rimless structure and relatively small amount of solid solution. That is among Ti(C0.7N0.3) phase exhibits a rimless structure and relatively small amount of solid solution. This is among Ti(C1-xNx) phases the dissolution rate of Ti(C0.3N0.7) is the lowest. Also fracture toughness(KIC) of the cermet was measured by indentation method. Attentions were paid to crack propagation path to look for a dominant fracture mode and to cor-relate it with fracture toughness values. The fracture toughness was relatively high with the addition of VC content. But the addition of a large VC content reduced the overall toughness of the cermet. This result is explained with the difference in fracture mode.

• 한국세라믹학회지
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• 제32권4호
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• pp.448-454
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• 1995

The effect of WO3 addition on microwave dielectric properties of BaTiO3-3{(1-x)TiO2-xWO3} system was studied. Addition of WO3 to this system resulted in the formation of BaWO4 and Ba2Ti9O20 phases. Both the dielectric constant (K) and the temperature coefficientof resonant frequency (Tf) were decreased with the amount of WO3 addition. The value of Q$\times$f0 was increased as the amount of WO3 was increased up to x=0.0275, and then decreased when x exceeded 0.03. At x=0.0275, this ceramic showed excellent microwave proprties of K=34-35, Q$\times$f0=50,000-53,000, and near zero ppm/$^{\circ}C$ of Tf.

• 한국세라믹학회지
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• 제16권4호
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• pp.225-236
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• 1979

The effect of $Ti^{+4}$ addition on the sinterability, microstructure, and temperature dependence of electromechanical coupling factor of magnetostrictive Ni-Cu-Co ferrite was investigated. The density of Ni-Cu-Co ferrite slightly increased by 2.0 mole % addition of either $TiO_2$ or $Fe_2TiO_4$, but tended to decrease by more than 2.0 mole % addition of $TiO_2$ or $Fe_2TiO_4$. As the content of either $TiO_2$ or $Fe_2TiO_4$ increased, the magnetocrystalline anisotropy compensation temperature also increased. Microstructure studies showed the stable grains when Ni-Cu-Co ferrite was sintered above 1, 20$0^{\circ}C$.

• 한국세라믹학회지
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• 제23권5호
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• pp.9-16
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• 1986

The effect of $TiO_2$ addition to the 90wt% Cordierite-10wt% Enstatite base glass was investi-gated to understand the crystallization behavior of the glass. Glasses with addition of $TiO_2$ less than 7, 5wt% had a tendency of surface crystallization and were cracked when heat treated and in this case the crystalline phase formed was indialite. glasses with addition of $TiO_2$ more than 10wt% to 15wt% were crystallized in bulk when heat treated and were suitable for glass-ceramics. The highest microhardness 1640kg/$mm^2$ was obtained when the glass of 12.5wt% $TiO_2$ addition was heat treated at 762$^{\circ}C$ for 60 minutes for nucleation and at 1135$^{\circ}C$ for 20 minutes for crystal growth and in general higher microhardness was obtained when crystalline phase of magnesium aluminum titanate and $\mu$-cordierite were developed. Avrami equation for crystal growth kinetics was applicable in glasses of less than 7.5 wt% $TiO_2$ addition and in case of glasses of more than 10wt% $TiO_2$ addition it was not applicable because of too fast crystal growth.

• 한국전기전자재료학회논문지
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• 제28권2호
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• pp.80-84
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• 2015

We investigated the dielectric relaxation properties $0.5Ba(Zr_{0.2}Ti_{0.8})O_3-0.5(Ba_{0.7}Ca_{0.3})TiO_3$ ceramics with CuO addition. With increasing CuO addition, the lattice parameter was increased by substitution of small amount $Cu^{2+}$ ion in B-site of $0.5Ba(Zr_{0.2}Ti_{0.8})O_3-0.5(Ba_{0.7}Ca_{0.3})TiO_3$ ceramics. Also the grain size and the maximum dielectric constant of $0.5Ba(Zr_{0.2}Ti_{0.8})O_3-0.5(Ba_{0.7}Ca_{0.3})TiO_3$ ceramics was decreased with increasing amounts of CuO addition. Moreover, the diffused phase transition properties (${\gamma}$) of $0.5Ba(Zr_{0.2}Ti_{0.8})O_3-0.5(Ba_{0.7}Ca_{0.3})TiO_3$ ceramics was increased by compositional fluctuation with increasing of CuO amount, changed from 1.45 at 1 wt% CuO addition to 1.94 at 7 wt% CuO addition.

• 한국세라믹학회지
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• 제33권2호
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• pp.223-227
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• 1996

The effect of ZrC and VC addition on the diffusion induced recrystallization (DIR) of TiC-Cr3C2 has been investigated. With in creasing the amount of added ZrC to Cr3C2 the DIR of TiC was suppressed at the begining and then occurred. On the contrary the DIR was accelerated with the addition of VC to Cr3C2 Because the lattice parameters of (Ti, Cr)C and (Ti,V)C are smaller and that of (Ti, Zr)C is larger than that of TiC the lattice parameter of (Ti,Cr,Zr)C is expected to be similar to that of TiC,. The results indicate that the strain energy due to lattice mismatch between TiC and solid-solution carbide is the driving force of the observed energy due to lattice mismatch between TiC and solid-solution carbide is the driving force of the observed DIR.