• Journal of Welding and Joining
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• v.26 no.4
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• pp.44-49
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• 2008

Generally, wear plate is steel plate having improved surface contact strength and impact strength by surface hardening which is welded using materials with good corrosion resistance, wear resistance and thermal resistance property. CFP GMAW(Compound Filler Plate Gas Metal Arc Welding) is the cladding method using GMAW with the CFP, which is bound with waterglass, on the substrate. It has advantages of reducing compound powder loss, uniform penetration, and preventing hardness decrease. To develope mass production technique of CFP GMAW process for production of high quality wear plate, the method for controling shallow penetration and increasing productivity is required. In this study, twin torch method applied to CFP GMAW process for increasing productivity. And the method was developed by controling penetration control, CFP dry time, gas formation flux and water glass concentration. As a result, applying twin torch method to CFP GMAW process was possible and high quality wide bead could be made without overlap joint.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.11a
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• pp.56-56
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• 2001

Ni-W alloy deposit is one of the best alternatives to hard chromium plating because of its good mechanical properties (high hardness, high strength, and good wear resistance). Ni-W alloy is deposited from weakly acidic or alkaline electrolytic bath with nickel sulfate, sodium tungstate or APT, and some kinds of organic hydroxy-acid complex and ammonia salts. W content of the deposit can be changed from 0 to 5Owt% and the coating with high W content is more attracted. But, meanwhile, the deposited layers are always found high internal stress, which cause them to become brittle and to bond insufficiently with the substrate. On the second hand, as the W content is incresed, the current efficiency reduced, which results in large quantities of hydrogen evolution and then produces bubbles on surface and pitting appearance In this paper, the influence of some additives on Ni-W alloy electroplating was investigated by means of compositional analysis and SEM. The initial results showed that 2-butyne-1,4-diol was the best brightener for Ni-W plating process. It could brighten and level deposit, but decreased the cathodic current efficiency. Its optimum concentration range is from O.lgjL to 0.5gjL. Besides, three kinds of additives including 2-butyne-1,4-diol were examined with Dagguchi method.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.2
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• pp.73-78
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• 2012

Recently, the laser processing method has used as micro-machining technologies in industries of aerospace, electronics and automotive. The laser processing newly focused could be alternative to existing machining method. However, there are few practical results of research about the proper setting of the laser machining conditions and the laser machining characteristics for mechanical materials. The purposes of this study was to choose optimum machining conditions and to estimate the laser machining characteristics using taguchi experimental method for various mechanical materials that is S45C, Stainless steel, Aluminum, Copper, Titanium and Tungsten carbide. From obtained results, it was confirmed that optimum machining conditions could be found and laser machinability depends on thermal conductivity and hardness of workpiece.

• Korean Journal of Metals and Materials
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• v.49 no.8
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• pp.628-634
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• 2011

SA508 Gr.4N Ni-Cr-Mo low alloy steel, in which Ni and Cr contents are higher than in commercial SA508 Gr.3 Mn-Mo-Ni low alloy steels, may be a candidate reactor pressure vessel (RPV) material with higher strength and toughness from its tempered martensitic microstructure. The inner surface of the RPV is weld-cladded with stainless steels to prevent corrosion. The goal of this study is to evaluate the microstructural properties of the clad interface between Ni-Cr-Mo low alloy steel and stainless weldment, and the effects of post weld heat treatment (PWHT) on the properties. The properties of the clad interface were compared with those of commercial Mn-Mo-Ni low alloy steel. Multi-layer welding of model alloys with ER308L and ER309L stainless steel by the SAW method was performed, and then PWHT was conducted at $610^{\circ}C$ for 30 h. The microstructural changes of the clad interface were analyzed using OM, SEM and TEM, and micro-Vickers hardness tests were performed. Before PWHT, the heat affected zone (HAZ) showed higher hardness than base and weld metals due to formation of martensite after welding in both steels. In addition, the hardness of the HAZ in Ni-Cr-Mo low alloy steel was higher than that in Mn-Mo-Ni low alloy steel due to a comparatively high martensite fraction. The hardness of the HAZ decreased after PWHT in both steels, but the dark region was formed near the fusion line in which the hardness was locally high. In the case of Mn-Mo-Ni low alloy steel, formation of fine Cr-carbides in the weld region near the fusion line by diffusion of C from the base metal resulted in locally high hardness in the dark region. However, the precipitates of the region in the Ni-Cr-Mo low alloy steel were similar to that in the base metal, and the hardness in the region was not greatly different from that in the base metal.

• Journal of the Korean institute of surface engineering
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• v.42 no.4
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• pp.173-178
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• 2009

DLC film was synthesized on plastic injection mold(SKD11, $30\;mm\;{\times}\;19\;mm\;{\times}\;0.5\;mm$) and Si(100) wafer for 2 h at $130^{\circ}C$ under 6 mTorr using hybrid method of rf sputtering and ion source. The obtained film was analysed by Raman spectroscopy, AFM, TEM, Nano indenter and scratch tester, etc. The film was defined as an amorphous phase. In the Raman spectrum, broad peak of $sp^2$-bonded carbon attributed to graphite at $1550\;cm^{-1}$ were observed, and the ratio of ID($sp^3$ diamond intensity)/IG($sp^2$ graphite intensity) was approximately 0.54. The adhesion of DLC film was more than 80 N with scratch tester when $0.2\;{\mu}m$ thickness Cr was coated as interlayer. The micro-hardness was distributed at 35~37 GPa. The friction coefficient was 0.02~0.07, and surface roughness(Ra) was 0.34~1.64 nm. The lifetime of DLC coated plastic injection mold using as a connector part in computer was more than 2 times of non-coated mold.

• Journal of the Korean Institute of Gas
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• v.14 no.6
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• pp.38-43
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• 2010

According to the lack of resources and the stringency of environmental regulations, a study of the high strength thin plate sheet steels for automobile have been become an important issue for automobile industry. However, the problem of hydrogen embrittlement of high strength sheet steels was concerned with the degradation of mechanical properties. Therefore, we studied the hydrogen behavior of surface layers of 590MPa DP sheet steels on development using by relationship the microstructure of subsurface and the distribution of micro hardnesses. Hydrogen was charged into the specimens using by the cathodic electrolytic method. The behavors of under surface layers were investigated by the observation of microstructures and the micro vickers hardness test with the amount of hydrogen charging with hydrogen charging conditions.

• Journal of the Korean Society of Safety
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• v.24 no.1
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• pp.1-6
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• 2009

In machining of ceramic materials, they are very difficult-to cut materials because of there high strength and hardness. Machining of ceramics are characterized by cracking and brittle fracture. Generally, ceramics are machined using conventional method such as grinding and polishing. However these processes are generally costly and have low MRR(material removal rate). This paper focuses on machinability evaluation of machinable ceramics for products with CNC machining center. Thus, in this paper, experiment applying cutting parameters is performed based on experimental design method. A design and analysis of experiments is conducted to study the effects of these parameters on the surface roughness by using the S/N ratio, analysis of ANOVA, and F-test. And multiple linear regression analysis is applied to compare experimental with predicted data in consideration of surface roughness. Cutting parameters, namely, feed, cutting speed and depth of cut are used to accomplish purpose of this paper. Required experiments are performed, and the results are investigated.

• Transactions on Electrical and Electronic Materials
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• v.18 no.3
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• pp.148-150
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• 2017

For the improvement of the anti-fouling features of porcelain electrical insulators, in this study, the surface of an insulator was coated with a functional material to expand the insulator's self-cleanness. The anti-fouling and mechanical features of the functional film coating of ceramic substrates made from components like an electrical insulator were analyzed. The coating methods that were used were spray coating, dip coating, and fabric coating. Following the coating, the contact angle of the coated surface was measured, revealing that the spray coating method offered the lowest angle ($13.7^{\circ}$) and a strong hydrophilic feature. The anti-fouling analysis showed that the anti-fouling features improved as the contact angle decreased. The mechanical properties - hardness and adhesion - were both excellent at 9H and 5B, respectively, regardless of the coating method that was used.

• Tribology and Lubricants
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• v.40 no.3
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• pp.91-96
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• 2024

Recently, extensive studies have been carried out to enhance various performance aspects such as the durability, lifespan, and hardness by combining diverse materials or developing novel materials. The utilization of superhydrophobic surfaces, particularly in the automotive, textile, and medical device industries, has gained momentum to achieve improved performance and efficiency. Superhydrophobicity refers to a surface state where the contact angle when water droplets fall is above 150°, while the contact angle during sliding motion is smaller than 10°. Superhydrophobic surfaces offer the advantage of water droplets not easily sliding off, maintaining a cleaner state as the droplets leave the surface. Surface modification involves two fundamental steps to achieve superhydrophobicity: surface roughness increase and surface energy reduction. However, existing methods, such as time-consuming processes and toxic organic precursors, still face challenges. In this study, we propose a method for superhydrophobic surface modification using lasers, aiming to create roughness in micro/nanostructures, ensuring durability while improving the production time and ease of fabrication. The mechanical durability of superhydrophobic samples treated with lasers is comparatively evaluated against chemical etching samples. The experimental results demonstrate superior mechanical durability through the laser treatment. Therefore, this research provides an effective and practical approach to superhydrophobic surface modification, highlighting the utility of laser treatment.

• Journal of Pharmaceutical Investigation
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• v.41 no.1
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• pp.51-57
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• 2011

The objective of this study was to enhance the utilitization of Ibuprofen (IBU) by introducing the fast-disintegrating tablet (FDT) form. Presently, IBU is being widely used as a tablet or syrup form. But in contrast to these two formulations, IBU as FDT is not only convenient but also increases the control over the time release of the drug, noted by using Alginate beads. This study was carried out with Sodium Alginate and IBU at the ratios of 1:0, 1:0.5, 1:1, and 1:2 in order to produce a series of beads with different ratios. During the drying process of the beads, talc was added in beads to compare the effects with and without the talc. The final product was scanned with SEM imaging to determine the difference in the surface of the beads. The parameters assessed were the diameter, content assay, dissolution test and effectiveness of time-release. Direct compression method was used to prepare FDT containing IBU bead. The properties of FDT, such as hardness, disintegration time, were investigated. The dissolution profiles of FDT were tested using KP dissolution apparatus 1 (basket method). The results suggest addition of talc and drying the beads made the surface smooth and less vulnerable to clutter into chunks. The size of beads was less than 300 ${\mu}m$ which did not create a sandy feeling in the mouth. Thus, the beads formulation model made the sustained release of the drug possible, the hardness of FDT (1.25~1.50 $Kg/cm^2$) was acceptable and all the values of dissolving period were less than 30 seconds. The dissolution profile of FDT was same as that of IBU bead. The efficient dissolution profile and low price of IBU bead containing Sodium Alginate, the FDT formulation prepared from IBU bead can save the expenses and can improve the convenience of application of this drug.