• Journal of the Korean institute of surface engineering
• /
• v.24 no.1
• /
• pp.34-34
• /
• 1991

Corrosion behavior of TiN coated steel was studied in terms of thickness of interlayer Ti and TiN coating TiN was are ion plated to a thickness of 1$\mu\textrm{m}$ and 2$\mu\textrm{m}$ respectively with interlayer coating of Ti of 1$\mu\textrm{m}$, 2$\mu\textrm{m}$ and 3$\mu\textrm{m}$. Corrosion resistance of TiN coated steel was evaluated by anodic palarization test in 1N H2SO4 as well as salt spray test. Porosity of each coating was also tested by using SO2 test method. Corrosion current density decreased with increasing TiN coating thickness and Ti interlayer coating markedly enhanced the corrosion resistance. Ti interlayer coating of 2$\mu\textrm{m}$ and 3$\mu\textrm{m}$ prior to 2$\mu\textrm{m}$ TiN coating decreased the corrosion current density of active range by an order of 4 and that of passive range by an order of 2. This improvement was associated with the retardation of corrosive agent penetration with increasing coating thickness and inherent corrosion resistance of Ti interlayer. Ti interlayer coating was also very effective in improvement of corrosion resistance under salt atmosphere.

• Journal of the Korean institute of surface engineering
• /
• v.25 no.1
• /
• pp.34-39
• /
• 1992

Corrosion behavior of TiN coated steel was studied in terms of thickness of interlayer Ti and TiN coating. TiN was arc ion plated to a thickness of 1$\mu\textrm{m}$ and 2$\mu\textrm{m}$ respectively with interlayer coating of Ti of 1$\mu\textrm{m}$, $2\mu\textrm{m}$ and $3\mu\textrm{m}$. Corrosion resistance of TiN coated steel was evaluated by anodic palarization test in 1N $H_2$SO$_4$ as well as salt spray test. Porosity of each coating was also tested by using $SO_2$ test method. Corrosion current density decreased with increasing TiN coating thickness and Ti interlayer coating markedly enhanced the corrosion resistance. Ti interlayer coating of $2\mu\textrm{m}$ and $3\mu\textrm{m}$ prior to $2\mu\textrm{m}$ TiN coating decreased the corrosion current density of active range by an order of 4 and that of passive range by an order of 2. This improvement was associated with the retardation of corrosive agent penetration with increasing coating thickness and inherent corrosion resistance of Ti interlayer. Ti interlayer coating was also very effective in improvement of corrosion resistance under salt atmosphere.

• Journal of the Korean institute of surface engineering
• /
• v.25 no.2
• /
• pp.82-89
• /
• 1992

The effect of interlayer coating of Ni and Ti on corrosion behavior was studied in TiN ion plated steel plate. Interlayer coating was carried out in a single and bi-layer to a various thickness combination prior to final TiN coating of $2\mu\textrm{m}$. Corrosion behavior was evaluated by anodic polarization test in 1N H2SO4 as well as salt spray test. Porosity of each coating was also tested by using SO2 test. Corrosion resistance was improved with increasing the thickness of Ni interlayer coating and Ni-Ti interlayer coating markedly enhanced the corrosion resistance. Ni/Ti interlayer coating of $2\mu\textrm{m}$/2$\mu\textrm{m}$ prior to $2\mu\textrm{m}$ TiN coating decreased the corrosion current density of active range by an order of 4 and that of passive range by an order of 1. This improvement was associated with the retardation of corrosive agent penetration with increasing coating thickness and inherent corrosion resistance of Ni and Ti interlayers, Ni/Ti interlayers coating were also very effective in improvement of corrosion resistance under salt atmosphere.

• Geotechnical Engineering
• /
• v.14 no.5
• /
• pp.163-172
• /
• 1998

To study the carrying capacity behavior of pile, dynamic pile testis and static load tests were carried out on two instrumented piles during and some time after pile driving. Cone Penetration Test( CPT) and Standard Penetration Test(SPT) were also performed at the test site before pile tests to investigate the relationship between unit skin friction of piles and cone tip resistance values and SPT N values. Total static capacity of pile reached the ultimate stage at the pile head settlement of about 0.055D (D : Pile diameter), at which skin friction of Pile already Passed the maximum value, but the end bearing was still increasing with the pile head settlement. The carrying capacity of pile increased in the form of natural logarithmic function with the time after pile driving. The increase in skin friction with time was very substantial the increase in skin friction 40 days after pile driving was 4.6 times of that determined during pile driving. The contribution of skin friction to the total capacity twas insignificant in the beginning, but became substantial 40 days after pile driving. This implies that the tested pile initially responded as an end bearing pile and later behaved as a friction pile. It was also noted that unit skin friction of pile might be ielated to cone tip resistance values(q.) and SPT N values, though the coefficient of this relationship might differ from one soil group to another and was somewhat greater than the value used in the design practice of Korea.

• Journal of Welding and Joining
• /
• v.14 no.6
• /
• pp.48-57
• /
• 1996

The weldability of high purity aluminum-lithium binary alloys has been investigated using the Varestraint test. Autogenous GTAW (gas-tungsten-arc-welds) were run along specimens of different lithium concentration using three sets of welding parameters. Welding voltage was held constant at 10 volts. Welding current (70∼100 amps) and travel speed (23∼33 cm/min) were the parameter varied. Hot-tearing susceptibility varied with lithium content and exhibited a steep peak at 2.6 weight percent lithium. Depth of penetration increased with increasing heat input and lithium concentration. The susceptibility is influenced by the wettability of dendrites by the interdendritic eutectic liquid as well as the time available for back-Siting by eutectic liquid. The welding condition of welding current 70A and travel speed 23 cm/min was showed good resistance to cracking in aluminum-lithium alloys. Suggestions for improving weld cracking resistance are also provided.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.10 no.4
• /
• pp.600-608
• /
• 2022

This study investigates the effect of layered double hydroxide (LDH) on the healing performance of self-healing concrete by assessing the chloride penetration resistance of self-healing cement mortars using electrical chloride ion migration-diffusion test. Test results show that both mortars containing healing materials only and mortars containing healing materials and Ca-Al LDH together mostly had higher migration-diffusion coefficients right after cracking, but the migration-diffusion coefficients decreased more than that of OPC with increasing healing ages, and thus, they yielded higher healing capacities than OPC. Also, mortars containing Ca-Al LDH together with healing materials showed higher reduction of their migration-diffusion coefficients, and thus, higher healing capacities than mortars containing healing materials only. This suggests that as the self-healing product increases on the crack surface, the binding of chloride ions by LDH inside the crack increases.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.4
• /
• pp.89-100
• /
• 2008

Applying graph and correlation developed in other countries to the domestic field has limits. Therefore, it is necessary that Piezocone factor should be determined by including ground characteristics obtained from various test results in the domestic site for better application. In this study, laboratory tests and field tests were performed to find the characteristics of soft ground which was widely distributed around Siwha lake. A comparative analysis of these tests with Piezocone penetration test was performed and the Piezocone factor was estimated by correlationship analysis of undrained shear strength and cone resistance. Also, an appropriate Piezocone factor in the study site was reestimated by utilizing statistical analysis method for deriving reliable result.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2013.11a
• /
• pp.179-182
• /
• 2013

Many kinds of fire-stop sealants have been used for joint sealing, cable penetration part sealing and fireproof structure finishing etc in building sectors which need water-proofing and fire-stop properties. But, fire-stop sealant itself has no specific industry standards in Korea even though there are so many required properties for the application. So, in this study, for the evaluation, we adopted and applied UL standard 94(UL 94) which is commonly used for the fire retardant testing in inflammable materials like plastics and rubbers in electronics industry. In this study, we demonstrated fire resistance properties of each fire-stop sealants which varied with different formulation, thickness and origins available in Korea. Overall, fire stop sealant had better fire resistance performance than normal construction sealant. And the thicker the material, the better the fire resistance performance was. Because there is no national or industry guideline for fire stop sealant itself, each sealant products showed different level of performances under UL94 desigation. Even certain product had very poor fire proof propeties although it claims it can be used for the application.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.19 no.6
• /
• pp.80-87
• /
• 2015

In this study, several properties of mortars made with calcium aluminate cement (CAC) such as hydrated products, strength characteristics, absorption, surface electric resistivity and chloride ions penetration resistance were experimentally investigated. The properties of CAC mortars were compared to those of ordinary portland cement (OPC) mortars. From the test results, it was found that the main hydrated products for CAC mortars were of $C_2AH_8$ and $CAH_{10}$, while CH, ettringite and calcite for OPC mortars. The surface electric resistivity and chloride ions penetration resistance of CAC mortars were significantly beneficial compared to those of OPC mortars. However, it should be noted that the absorption properties of CAC mortars were negatively examined. Thus, it needs to have more study for the improvement of surface absorption of CAC matrices. In addition, the combined mixture of CAC and OPC were ineffective to improve some performances of mortars.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.3
• /
• pp.661-667
• /
• 2016

This study evaluated the potential of methodology development of the helical type anchor for soft ground applications. The rotational penetration of the helix structure might make construction-steps easy without the soil spitting and reusable rods could reduce the material cost. Removal of the anchors would be simple as a construction, which can be named the removal anchor. The anchoring resistance after construction is strongly related to the number of helixes resulting in a concise design process. The investigation involved a chamber test with soft soils. In the test, a specially designed and fabricated helical anchor and torque-driver were used to obtain the maximum pull-out resistance of the anchor after rotational penetration. As a result of the tests, The rotational torque and pull-out resistance have a proportional relationship with the strength of the prepared soils. Within the range of the study, the torque of the anchor penetrating increased with increasing pull-out resistance.