• Journal of Surface Science and Engineering
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• v.44 no.6
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• pp.269-276
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• 2011

Phase evolution and tribological behavior of Cr-Mo-N multi compositional films with different interlayer were investigated. The films were deposited by hybrid PVD (Physical Vapor Deposition) system consisted of dc unbalanced magnetron (UBM) sputtering and arc ion plating (AIP) sources. A pure molybdenum (Mo) was used as sputtering target and also a pure Cr was used as AIP target to form the Cr-Mo-N films. Various growth planes were found, no textured surface, in all of the multi composition films. Maximum value of microhardness was measured in Cr-Mo-N film with Mo interlayer as 29 GPa. Composition film was mainly showed the aspect of the adhesive wear than CrN film. The friction coefficient was decreased from 0.6 for pure CrN coating to 0.35 for Cr-Mo-N film with Mo interlayer. This result may come from the formation of metal oxide tribo-layer which is known as solid lubricant during the wear test.

• Korean Journal of Materials Research
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• v.28 no.7
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• pp.405-410
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• 2018

TiN and CrN thin films are among the most used coatings in machine and tool steels. TiN and CrN are deposited by arc ion plating(AIP) method. The AIP method inhibits the reaction by depositing a hard, protective coating on the material surface. In this study, the characteristics of multi-layer(TiN/CrN/TiN(TCT), CrN/TiN/CrN(CTC)) are investigated. For comparison, TiN with the same thickness as the multilayer is formed as a single layer and analyzed. Thin films formed as multilayers are well stacked. The characteristics of micro hardness and corrosion resistance are better than those of single layer TiN. The TiN/CrN peak is confirmed because both TCT and CTC are formed of the same component(TiN, CrN), and the phase is first grown in the (111) direction, which is the growth direction. However, the adhesion and abrasion resistance of the multilayer films are somewhat lower.

• Journal of the Semiconductor & Display Technology
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• v.14 no.1
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• pp.67-71
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• 2015

Pulse electroplating was studied to form nanocrystal structure effectively by changing plating current density and duty cycle. When both of plating current density and duty cycle were decreased from $100mA/cm^2$ and 70% to $50mA/cm^2$ and 30%, the P content in the Ni matrix was increased almost up to the composition of $Ni_3P$ compound and the grain growth after annealing was retarded as well. The as-plated hardness values ranging from 660 to 753 HV are mainly based on the formation of nanocrystal structure. On the other hand, the post-anneal hardness values ranging from 898 to 1045 HV, which are comparable to the hardness of hard Cr, are coming from how competition worked between the precipitation of $Ni_3P$ and the grain coarsening. According to the ANOVA and regression analysis, the plating current density showed more strong effect on nanocrystal size and film hardness than the duty cycle.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2002.05a
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• pp.36-36
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• 2002

Effects of pulse-plating on the wear and corrosion resistance of chrome-carbon layers were studied. The plating were carried out at $06A/\textrm{cm}^2$ in modified Sargent bath containing formic acid at $53^{\circ}C$. The chrome layer were super-saturated with carbon up to 2.0wt. %, which precipitated as chrome carbide such as $Cr_{23}C_6$ after vacuum aging above $200^{\circ}C$ for 1 hour. This resulted in improvement of hardness and wear resistance of the chrome layer. Considering the reduction of corrosion resistance due to the thermal effect, optimum vacuum aging condition of the chrome layer in this study was I-hour at $200^{\circ}C$.

• Journal of Surface Science and Engineering
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• v.32 no.3
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• pp.265-275
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• 1999

Titanium nitride and related overlayers produced by arc ion plating (AIP) are applied as commercial coatings in world-wide scale since the middle of 80s. Due to the achievements of low temperature deposition (LTD), they begin now to be used as wear and corrosion-resistant coatings for machine parts, besides applications on cemented carbide and high speed steel cutting tools. On the other side, TiN can be now applied successfully to brass, Al-alloy, ZnAl alloy articles as decorative coating through LTD. Various nitrides, carbonitrides, borides and other refractory compounds, such as (Ti, Al)N, TiCN, CrN, are used as the coatings for special heavy-duty working conditions instead of TiN since 90s. More and more multilayer coatings are applied now substituting single layer ones. Duplex processes are under development.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2008.11a
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• pp.153-154
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• 2008

High velocity oxy-fuel (HVOF) thermal spraying coating has been used widely throughout the last 60 years mainly in defense, aerospace, and power plants. Recently this coating technique is considered as a promising candidate for the replacement of the traditional electrolytic hard chrome plating (EHC) which pollutes the environment and causes lung cancer by toxic hexa-valent $Cr^{6+}$. In this study, two kinds of cermet coatings, WC-CoCr and WC-CrC-Ni, are formed by HVOF spraying. The wear properties of coatings are evaluated comparatively by reciprocating sliding wear tests at $25^{\circ}C$, $250^{\circ}C$ and $450^{\circ}C$ respectively. Wear rates show that WC-CoCr coatings have better sliding wear resistance than WC-CrC-Ni coatings regardless of temperature due to more, compact and homogeneously distributed WC particles, less metal content, Co, Cr rich metallic bindermatrix with higher fracture strength and better adhesive strength with WC particles.

• Journal of Surface Science and Engineering
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• v.36 no.3
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• pp.256-262
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• 2003

The current efficiency and the composition of Zn-Cr and Zn-Cr-X (X : Co, Mn) alloy electrodeposits were investigated by using chloride bath with EDTA auditive and flow cell plating system. The current efficiency of Zn-Cr alloy decreased with increasing current density, while it increased with the content of Co and Mn of the Zn-Cr-X alloy bath in high current density region. The Cr content in Zn-Cr alloy increased from 1.4-2.7 to $28wt\%$ with increasing current density and the phase structure of the alloys changed from $\eta-Zn$ through $\eta-Zn+\gamma'-ZnCr\;to\;\gamma'-ZnCr$ with Increasing Cr content of the alloys. The Co content in Zn-Cr-Co alloys increased with Co content of the bath, while Cr content of the alloy increased or decreased in low current density region $(10-75A/dm^2)$ or high current density region $(75-100A/dm^2)$, respectively. $\gamma-ZnCo$ phase was formed in the Zn-Cr-Co alloy with above $9.0wt\%$ Co. The content of Mn and Cr in Zn-Cr-Mn alloys increased or decreased with the increase of current density in high current density region, respectively while Cr content of the alloy decreased noticeably with the increase of Mn content in the bath. Two phases of $\delta_1-ZnMn$ and $\gamma'-ZnCr$ were formed in the Zn-Cr-Mn alloy with above $8.6wt\%$ Mn.

• Journal of Surface Science and Engineering
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• v.37 no.3
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• pp.179-184
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• 2004

Hard chromium coating technology using hexavalent chromium bath is widely used in various industries. Because of the serious health and environmental problems of hexavalent chromium, many attempts to alternate the hexavalent chromium plating have been made over 50 years. Trivalent chromium plating is one of the challengeable technologies to alternate hexavalent chromium plating. It is relatively none-toxic. Although some papers have described hard chromium coatings produced from trivalent chromium solution, it has limited the industrialization because of chemical and electrochemical problems of trivalent chromium ions. This paper introduces a number of factors for successful trivalent chromium plating, to give a some information about trivalent chromium process.

• Journal of Surface Science and Engineering
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• v.14 no.4
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• pp.215-220
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• 1981

The surface appearance of chromium electrodeposit was studied by employing a pulse curr-ent plating in self-regulating high speed (SRHS) bath containing 20 g/$\ell$, K2SiF6 7.5 g/$\ell$ SrSO4 and 250 g/$\ell$ CrO3. As the pulse frequency increased, the surface appearance changed suddenly from bright a-ppearance in a direct current plating condition to gray one in the range of pulse frequency less than about 20KHz. However the bright appearance is recovered as the pulse frequen-cy exceeded 20 KHz. This phenomena seemed to be related with the preferred orientation of electrodeposits, considering the relationship between the preferred orientation of elect-rodeposits and surface appearance in a SRHS bath. Direct current plating was also applied to both Sargent and SRHS bath and investigat-ion on surface appearance was extended to the high current density of 400 A/dm2. In a Sa-rgent bath, the increase in bath temperature was necessary for bright appearance as the current density was increased within 150 A/dm2, but bright region was shown in the cons-tant temperature of 70-75$^{\circ}C$ above the current density of 150A/dm2. On the other hand, two regions of surface brightness was found in a SRHS bath. One is region in the low temperature less than 25$^{\circ}C$ and the other in the moderate temperature range from 55$^{\circ}C$ to 65$^{\circ}C$.

• Environmental Analysis Health and Toxicology
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• v.21 no.4 s.55
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• pp.357-363
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• 2006

Chromium compounds are widely used in diverse industries including pigment manufacturing, painting, metal plating and leather tanning. With the wide uses of chromium, various adverse effects of the compounds on the environment and human health have been reported. Among them, hexavalent chromium [Cr (VI)], which is a carcinogenic heavy metal, has been widely studies. Epidemiological investigations have shown that respiratory cancers had been found in workers who had been occupationally exposed to Cr (VI). In this study, cell toxicity and induction of reactive oxygen species (ROS) by Cr (VI) (1, 2, 4, $8{\mu}M$) in cultured human bronchial epithelial cells were investigated. Exposure of the cells to Cr (VI) led to cell death, ROS increase, and cytosolic caspase-3 activation. The ROS increase was related with the decreased level of GSH. Chromatin condensation and fragmentation were occurred by Cr (VI) when evaluated by DAPI staining or agarose gel electrophoresis of the extracted DNA. Expression of ROS related genes including glutathione S-transferase, heme oxygenase-1, metallothionein were significantly induced in Cr (VI) treated cells. This result suggests the toxicity in cultured cells by Cr (VI) was expressed through the apoptotic process with ROS induction.