• Journal of the Korean institute of surface engineering
• /
• v.34 no.3
• /
• pp.195-205
• /
• 2001

The surface characteristics of Ti/TiN films coated on sintered stainless steels (SSS) by electron beam physical vapour deposition (EB-PVD) were investigated. Stainless steel compacts containing 2, 4, and 10wt%Cu were prepared by the electroless Cu-plating method, which results in increased homogenization in the alloying powder. The specimens were coated with Ti and TiN with a 1.0$\mu\textrm{m}$ thickness respectively by EB-PVD. The microstructures were investigated using scanning electron microscopy (SEM). The corrosion behaviors were investigated using a potentiosat in 0.1 M $H_2$$SO_4$, and 0.1M HCl solutions and the corrosion surface was observed using SEM and XPS. The Ti coated specimens showed rough surface compared to Ti/TiN coated specimens. Ti and Ti/TiN coated SSS revealed a higher corrosion and pitting potential from anodic polarization curves than that of Ti and Ti/TiN uncoated SSS. In addition, Ti/TiN coated SSS containing 10wt% Cu exhibited good resistance to pitting corrosion due to the formation of a dense film on the surface and the decrease in interconnected porosity by electroless coated Cu.

• Journal of the Korean institute of surface engineering
• /
• v.30 no.1
• /
• pp.33-43
• /
• 1997

The effects of process parameters substrate such as substrate current and substrate temperature on the corrosion resistance of ion plated TiN film were investigated. TiN fims were deposited on speed steel on which Ti or Ni hed been previously evaporated. Dense TiN films could be obtained under higher substrate current(1A) and substrate temperature($500^{\circ}C$), whereas TiN films deposited with lower substances current(0.5A) and substrate temperature($300^{\circ}C$) showed porous structure. The corrosion resistances of high speed steel was considerably increased when dense TiN films had been formed on it. The effect of Ti and Ni interlayer on the increase of the corrosion resistance was also significant with dense TiN films, while there was little effect of interlayer on the corrosion resistance when TiN films were porous. the effect of interlayer on the corrosion resistance was more outstanding with Ti then with Ni, because Ti reacts more easily with oxygen to form an oxide layer, and it also shows higher resistance against chlorine containing corrosion media.

• 한국전자현미경학회:학술대회논문집
• /
• 2001.05a
• /
• pp.69-72
• /
• 2001

• Korean Journal of Materials Research
• /
• v.13 no.10
• /
• pp.683-690
• /
• 2003

The high strength low alloy(HSLA) steels microalloyed with Nb, Ti and V have been widely used as the automobile parts to decrease weight of vehicles. The effects of process conditions are investigated in the aspects of the precipitation behavior and the mechanical properties of HSLA steel microalloyed with Nb and Ti using TEM, SANS and mechanical testing. When Ti was added to a 0.07C-1.7Mn steel which was coiled at $500^{\circ}C$, the specimen revealed the property of higher tensile strength of 853.1 MPa and the stretch-flangeability of 60%. The stretch-flangeability was increased up to 97.8% for coiling temperature above $700^{\circ}C$. The precipitation hardening cannot be achieved in the 0.045C-1.65Mn steel which was the lower density of fine precipitates. However, the 0.07C-1.7Mn steels containing Nb and/or Ti which was coiled at X$/^{\circ}C$ have a high precipitates density of $2${\times}$10^{ 5}$/$\mu$㎥. The high strength of these steels was attributed to the precipitation hardening caused by a large volume froction of (Ti, Nb)C precipitates with a size below 5 nm in ferrite matrix.

• Journal of Powder Materials
• /
• v.4 no.4
• /
• pp.243-251
• /
• 1997

Engine valve-shaped TiAl-Mn intermetallics containing 43.5 to 47.5at%Al (Mn/Al=0.036) are successively fabricated by reactive sintering the elemental powder mixtures near-net shaped by extrusion and die forging. A duplex structure consisted of lamellar grains and equiaxed $\gamma$ grains is developed for all compositions, and the areal fraction of the lamellar grains(or equiaxed $\gamma$ grains) decreases (or increases) with increasing Al content. As Al content increased, the elongation increases with accompanying decrease in yield strength and ultimate tensile strength at both room temperature and 80$0^{\circ}C$. This indicates that the suitable composition is Ti-45at%Al-1.6at%Mn in considering the balance of ambient and elevated tensile properties. The reactive-sintered Ti-45Al-1.6Mn alloy shows superior oxidation resistance not only to the plasma arc melted one but also to the heat resistance steel STR35(representative exhaust valve head material for automotive engine). The reactive-sintered Ti-45Al-1.6Mn alloy coated with an oxidizing scale exhibits a better wear resistance than induction hardened martensitic steel STR11(representative exhaust valve tip material for automotive engine).

• Coupled systems mechanics
• /
• v.9 no.3
• /
• pp.281-287
• /
• 2020

Nanotechnology is an upcoming technology that can provide solution for combating pollution by controlling shape and size of materials at the nanoscale. This review provides comprehensive information regarding the role of nanotechnology in pollution control at concrete structures. Titanium dioxide (TiO2) nanoparticles are a good item for concrete structures for diminishing the air polluting affect by gasses of exhaust. In this article, the mixture rule is presented for the effect of nanoparticles in environmental pollution reduction in concrete structures. The compressive strength, elastic modulus and reduction of steel bars in the concrete structures are studied. The Results show that TiO2 nanoparticles have significant effect on the reduction of environmental pollution and increase of stiffness in the concrete structures. In addition, the nanoparticles can reduce the use of steel bars in the concrete structure.

• Korean Journal of Metals and Materials
• /
• v.46 no.4
• /
• pp.199-208
• /
• 2008

This study is concerned with effects of complex oxides on Charpy impact toughness of heat affected zone (HAZ) of API X80 linepipe steels. Three kinds of steels were fabricated by varying alloying elements such as Ti, Al, and Mg and hot-rolling conditions to form complex oxides, and their microstructures and Charpy impact properties were investigated. The number of complex oxides present in the steel containing excess Ti, Al, and Mg was twice larger than that in the conventional steels, while their size ranged from 1 to $3{\mu}m$ in the three steels. After the HAZ simulation test, the steel containing a number of oxides contained about 20 vol.% of acicular ferrite in the simulated HAZ, together with bainitic ferrite and martensite, whereas the HAZ microstructure of the conventional steels consisted of bainitic ferrite and martensite with a small amount of acicular ferrite. This formation of acicular ferrite in the oxide-containing steel was associated with the nucleation of acicular ferrite at complex oxides, thereby leading to the great (five times or more) improvement of Charpy impact toughness over the conventional steels.

• Progress in Superconductivity and Cryogenics
• /
• v.19 no.1
• /
• pp.22-25
• /
• 2017

Steel slag has been considered as an industrial waste. A huge amount of slag is produced as a byproduct and the steel slag usually has been dumped in a landfill site. However the steel slag contains valuable resources such as iron, copper, manganese, and magnesium. Superconducting magnetic separation has been applied on recovery of the valuable resources from the steel slag and this process also has intended to reduce the waste to be dumped. Cryo-cooled Nb-Ti superconducting magnet with 100 mm bore and 600 mm of height was used as the magnetic separator. The separating efficiency was evaluated in the function of magnetic field. A steel slag was ground and analyzed for the composition. Iron containing minerals were successfully concentrated from less iron containing portion. The separation efficiency was highly dependent on the particle size giving higher separating efficiency with finer particle. The magnetic field also effects on the separation ratio. Current study showed that an appropriate grinding of slag and magnetic separation lead to the recovery of metal resources from steel slag waste rather than dumping all of the volume.

• Journal of Technologic Dentistry
• /
• v.23 no.1
• /
• pp.21-30
• /
• 2001

For biomedical applications. Ti-X%Zr-Y%Pd(X: $10{\sim}20$, Y:0.2 or 0.4) based alloys not containing harmful Al and V were newly designed, and polarization curves for their alloys were measured at $37^{\circ}C$ in 5% HCl solution in order to understand effects of Zr on the corrosion. From the results of anodic polarization behavior, it was found that the corrosion resistance increased with increasing Zr content. The results show their potential to develope Ti-based alloys for biomedical materials. The Ti-20%Zr-0.2%Pd alloy shows excellent corrosion resistance and was superior to those of the Ti. Ti-6%Al-4%V ELI alloy, Co-30%Cr-6%Mo alloy and STS 316L stainless steel.

• Journal of environmental and Sanitary engineering
• /
• v.16 no.2
• /
• pp.47-55
• /
• 2001

We investigated to find the optimum operation condition of electrolysis which have an influence on removal efficiency of heavy metals. When we experimented the testing wastewaters containing each 250mg/L of Cu and Ni ions, we got the variables like as pH, amount of electrolyte(NaCl), different species of electrode, electrode gap, electric strength, the number of electrodes, after fastening positive electrode plate with Al, Fe, Ti and negative electrode plate with Stainless Steel plate.