• Journal of Powder Materials
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• v.19 no.3
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• pp.189-195
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• 2012

A novel PM (powder metallurgy) steel for automotive power-train gear components was developed to reduce manufacturing cost, while meeting application requirements. The high-density PM steel was manufactured by mixing using special Cr-Mo atomized iron powders, high-pressure compaction, and sintering. Tensile strength, charpy impact, bending fatigue, and contact fatigue tests for the PM steel were carried out and compared to conventional forged steel. Pinion gears for auto-transmission were also manufactured by helical pressing, sintering, and surface densification process. In order to evaluate the durability of the PM parts, auto-transmission durability tests were performed using dynamometer tests. Results showed that the PM steel fulfilled the requirements for pinion gears indicating suitable tensile, bending fatigue, contact fatigue strengths and improved gear tooth profile. The PM gears also showed good performance during the transmission durability tests. As a result, the PM gears showed significant potential to replace the conventional forged steel gears manufactured by tooth machining (hobbing, shaving, and grinding) processes.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.578-579
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• 2006

We investigated that the effect of $CaCO_3$ based compound on machinability of two types of PM steels. One is a copper steel which is selected as a general PM steel, and the other is a diffusion alloyed steel selected as a high strength PM steel. It is found that $CaCO_3$ based compound addition improves machinability in drilling of both of the PM steels. Although the compound addition degrades the mechanical properties of PM steels, it is considered that decrease of the properties can be compensated by increasing density.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.3
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• pp.329-341
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• 2016

Pohang is a well-known industrial city in Korea with a large steel-industrial complexes. The biggest environmental issue in the city is associated with fine particulate matter (hereinafter, $PM_{10}$). The concentration of $PM_{10}$ is generally dependent on the local emission sources and meteorological conditions. Iron and steel industrial complexes are likely serious pollution sources of $PM_{10}$ in Pohang. In this study, daily $PM_{10}$ data from a large database from the year of 2000 to 2012 were statistically analyzed, together with meteorological data. The average concentrations of $PM_{10}$ were evaluated according to the frequency of Asian dust, haze, mist, and fog. The number of days exceeding short-term standard for $PM_{10}$ were also examined, taking into consideration of weather conditions. It was found that the concentration of $PM_{10}$ was reduced about 18% to 26% because of precipitation. In addition, the effects of wind direction and wind speed on the $PM_{10}$ concentrations were investigated.

• Tribology and Lubricants
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• v.19 no.1
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• pp.1-8
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• 2003

Recently, PM-high speed steel(PM-HSS) has reportedly been a good alternative material for rolling mill because of its superior performance to conventional HSS. This paper has been aimed to investigate the possibility for application to rolling contact element for PM-HSS by X-ray diffraction technique. The X-ray elastic constant for PH-HSS has been found by X-ray diffraction during the four-point bending test. Residual stress and half-value breadth on the contact surface during rolling contact fatigue process by X-ray diffraction have also been measured. The result of this study shows that the application of X-ray diffraction technique to PM-HSS could be as possible alternative material as conventional HSS. Half-value breadth on rolling contact surface by X-ray diffraction is not changed during rolling contact fatigue process. On the other hand, the residual stress is changed. This suggests that dislocation reaction has been hardly occurred in rolling contact, depending on super-saturated carbon in PM-HSS.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1993.11a
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• pp.4-4
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• 1993

Ferrous powder metallurgy in Japan has developed in the last four decades, where every decade is featured by certain breakthroughs in materials. The progress in PM materials is closely related to newly developed powders. Low alloy steel powders for high strength PM components are grouped into three types: Ni and/or Mo containing completely alloyed powders, Ni containing partially alloyed powders, and Cr containing completely alloyed powders. Every type has its special characteristics. The tensile strength of PM materials is improved up to 2 GPa. The hardness is also increased to exceed 500 HV with normal hardening methods, and 700 HV with novel surface treatment techniques. The present maximum of fatigue strength is 550 MPa, and that of impact energy is 100 J. Novel PM materials with improved properties are applied to a variety of automobile and other components: power steering pumps, rocker anns, valve guides and inserts, bearings, torque sensors, etc. The future outlook for the ferrous PM is Quite positive, and the industry is expected to show renewed growth by applying many types of alloy steel powders and new ferrous PM materials.

• Tribology and Lubricants
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• v.15 no.2
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• pp.156-163
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• 1999

The mechanical characteristics of the high speed steel by Powder metallurgy Process (PM-HSS) has been reported to improve with several alloying constituents, such as high carbon, vanadium and cobalt. In this paper, sliding wear test has been conducted using a pin-on-disc machine for three PM-HSS which contains 0%, 5% and 12% cobalt respectively, in order to evaluate the effect of cobalt on wear properties of PM-HSS. The results of this study showed that the wear resistance of PM-HSS has been increased by the addition of cobalt on the range of experimental friction velocities. When compared with the effect of addition of cobalt, the wear resistance of PM-HSS with 5% cobalt has been found to be superior to that of PM-HSS with 12% cobalt.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5601-5609
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• 2012

The fine particulate matter($PM_{10}$) concentrations and contents were measured to check the health and environment influential factors in Pohang Iron and Steel Industrial Complex and its vicinities. In addition, the $PM_{10}$ distribution for each year and season was surveyed using the regional air quality monitoring stations. The measuring on the $PM_{10}$ inside the industrial complex showed $61.3{\pm}12.1{\mu}g/m^3$ for average concentration of $PM_{10}$ which was measured by Dongil Industry and $44.3{\pm}8.1{\mu}g/m^3$ measured by steel manufacturing industry complex management office. Both of them satisfied the environmental air quality standard. The percentage of $SO_4{^2}$, $NO_3{^-}$, $NH_4{^+}$ which are the secondary ions created out of the $PM_{10}$ in Dongil Industry and steel manufacturing industry complex management office was checked and it was revealed that the percentage of ${SO_4}^{2-}$ was high and it is considered that the pollution source related with the sulfides exist at the industrial complex. They were in order of ${SO_4}^{2-}$ > $Cl^-$ > $NO_3{^-}$ > $F^-$ > $NH_4{^+}$ in Dongil Industry and ${SO_4}^{2-}$ > $Cl^-$ > $NO_3{^-}$ > $NH_4{^+}$ > $F^-$ in steel manufacturing industry complex management office.

• Journal of Sensor Science and Technology
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• v.11 no.3
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• pp.138-144
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• 2002

The silicon piezoresistive pressure sensor is made by semiconductor process to obtain stainless steel isolated type pressure sensor. The sensor is loaded on a stainless steel housing with glass molding, $50\;{\mu}m$ stainless steel thin film is welded, and the stainless steel housing encapsulated by silicone oil. The performance of fabricated the pressure sensor has 10 bar pressure range. The XTR105 of exclusive transmitter chip is used the pressure transmitter that output current is 4 - 20 mA. The accuracy is ${\pm}5%$ FS, however, the accuracy is ${\pm}1%$ FS when the sensor is compensated temperature.

• The Journal of Advanced Prosthodontics
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• v.8 no.1
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• pp.43-52
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• 2016

PURPOSE. This study was conducted to evaluate the effects of full-coverage all-ceramic zirconia, lithium disilicate glass-ceramic, leucite glass-ceramic, or stainless steel crowns on antagonistic primary tooth wear. MATERIALS AND METHODS. There were four study groups: the stainless steel (Steel) group, the leucite glass-ceramic (Leucite) group, the lithium disilicate glass-ceramic (Lithium) group, and the monolithic zirconia (Zirconia) group. Ten flat crown specimens were prepared per group; opposing teeth were prepared using primary canines. A wear test was conducted over 100,000 chewing cycles using a dual-axis chewing simulator and a 50 N masticating force, and wear losses of antagonistic teeth and restorative materials were calculated using a three-dimensional profiling system and an electronic scale, respectively. Statistical significance was determined using One-way ANOVA and Tukey's test (P<.05). RESULTS. The Leucite group ($2.670{\pm}1.471mm^3$) showed the greatest amount of antagonist tooth wear, followed by in decreasing order by the Lithium ($2.042{\pm}0.696mm^3$), Zirconia ($1.426{\pm}0.477mm^3$), and Steel groups ($0.397{\pm}0.192mm^3$). Mean volume losses in the Leucite and Lithium groups were significantly greater than in the Steel group (P<.05). No significant difference was observed between mean volume losses in the Zirconia and Steel groups (P>.05). CONCLUSION. Leucite glass-ceramic and lithium disilicate glass-ceramic cause more primary tooth wear than stainless steel or zirconia.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.11a
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• pp.44-49
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• 2000

Recently, PM-high speed steel(PM-HSS) has reportedly been a good alternative material for rolling mill because of its superior peformance to conventional HSS. This paper has been aimed to investigate the possibility for application to rolling contact element for PM-HSS by X-ray diffraction technique. The X-ray elastic constant for PM-HSS has been found by X-ray diffraction during the four-point bending test. Residual stress and half-value breadth on the contact surface during rolling contact fatigue process by X-ray diffraction have also been measured. The result of this study shows that the application of X-ray diffraction technique to PM-HSS could be as possible alternative material as conventional HSS. Half-value breadth on rolling contact surface by X-ray diffraction is not changed during rolling contact fatigue process. On the other hand, the residual stress is changed. This suggests that dislocation reaction has been hardly occurred in rolling contact, depending on supersaturated carbon in PM-HSS.