• 열처리공학회지
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• 제29권6호
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• pp.284-291
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• 2016

High temperature alloy steel such as Ni-Cr-Mo-V material has excellent properties of high strength and high heating resistance. It has been used for several military weapon components such as gun barrel of a warship, turbine rotor and turbine disk for nuclear power plant. Being curious about this material required excellent wear resistance and durability in extreme environmental conditions. A dry wear test at the ambient air and Ar gas conditions in the room temperature were performed in this study. What's more a lubricant wear test at different temperature was conducted. In addition that DLC was coated on Ni-Cr-Mo-V alloy steel substrate with a thickness of $3{\mu}m$, a property of it was compare with lubricant conditions. All the coefficient of friction and wear volume, comparing with DLC coated specimens. The test parameters were selected as follows: 10 N for normal load; 80 rpm for sliding wear speed; and 300 m for the sliding wear distance.

• 열처리공학회지
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• 제27권2호
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• pp.65-71
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• 2014

SMF9060 material is a Fe-based powder sintered alloy that is used for several automobile components such as Synchronize Hub, oil pump and transmission. These components are required excellent wear resistance and durability. In this study, we have performed a dry wear test at the ambient air and Ar gas conditions in the room temperature, and a lubricant wear test at the room temperature and engine oil temperature of $100^{\circ}C$. The amount of wear volume and coefficient friction are measured by a Profilometer and a Ball on disk type wear tester. The wear volume in Ar gas condition was a little higher than that in the ambient air condition. However the wear volume in the lubricant wear condition was much lower than in the dry wear condition. XRD analysis of the debris in Ar gas condition showed that the oxide film was not formed.

• Tribology and Lubricants
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• 제35권5호
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• pp.317-322
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• 2019

In spite of progress in tribological research, machine component failure due to friction and wear has been reported frequently. This failure may lead to secondary damage that can cause huge expense for maintenance and repair. To prevent economic loss, it is important to detect and predict the initial failure point. In this sense, various researchers have been tried to develop Condition Monitoring (CM) method using Acoustic Emission (AE) generated while the materials undergo failure. In this study, effect of particles on friction and wear was investigated using the pin-on-plate friction test and AE signal was recorded with a band-width type AE sensor. The experiments were performed in dry and lubricant conditions using steel and glass as specimens. After the experiment, 3D laser microscope image was captured to evaluate the wear behavior quantitatively. The AE signal was analyzed in time-domain and frequency-domain. The amplitude was compared with the frictional results. The results of this study showed that particle generation accelerate wear, generate high magnitude AE signal and change the frequency characteristics of the signal. Also, lubricant condition test results showed low coefficient of friction, low wear rate, and low magnitude of AE signal compared to the dry condition. It is expected that the results of this study will aid in better assessment of wear in CM technology

• Tribology and Lubricants
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• 제34권6호
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• pp.254-261
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• 2018

In order to reduce resistance torque and energy loss, minimizing friction between race surface and rolling elements of a bearing is necessary. Recently, to reduce friction in bearing element, solid lubricant coating for the bearing raceway surface has been receiving much attention. Considering the operating conditions of real bearings, verifying the effect of solid lubricant coatings under extreme conditions of high load that is more than 1 GPa is necessary. In this study, we evaluated the friction and wear characteristics of SUJ2 bearing steels deposited by carbon-based coatings (Si-DLC, ta-C), $MoS_2$ and graphite. In case of $MoS_2$ and graphite coatings, different surface treatments were applied to the coatings to verify the effect of surface treatment. A pin-on-disc type tribotester was used to evaluate the tribological characteristics of the coatings. It was possible to quantitatively estimate the friction and wear characteristics of solid lubricant under dry and lubrication conditions. The carbon-based coatings improved the friction and wear properties of SUJ2 bearing steels under the high load condition, but $MoS_2$ and graphite coatings were not suitable for high load conditions due to its low hardness. Different friction and wear behaviors were found for different substrate surface treatment method. Also, it was confirmed that solid lubricant coatings had a more positive effect than just applying the lubricant for improving the tribological characteristics.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.391-392
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• 2006

Sintered materials have been applied widely in Valve Seat Inserts (VSI). The amount of wear on VSIs increases when used in gas (LPG, CNG) engines because of their dry environments. In this paper, two newly developed high performance VSI materials for gas engines are introduced. These materials applied new techniques, which are both high performance hard particle and new distribution method of solid lubricant, to increase wear resistance.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.245-250
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• 2003

This research conducted milling tests to study effects of cutting environment conditions of ball end mills on the characteristics of hard milling process. KP4 steels and STD11 heat treated steels were used as the workpiece and WC-Co ball end mill tools with TiAIN coated were utilized in the cutting tests. Dry cutting without coolant and semi-dry cutting using botanical oil coolant were conducted and MQL (Minimum Quantity Lubricant) device was used to spray coolant. Cutting forces, tool wear and surface roughness were measured in the cutting tests. Results showed that dry cutting of KP4 and hardened STD11 specimens produced better surface quality and wear performance than MQL spray cutting did.

• 소성∙가공
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• 제13권1호
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• pp.45-52
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• 2004

This research conducted milling tests to study effects of cutting environment conditions of ball end mills on the characteristics of hard milling process. KP4 steels and STD11 heat treated steels were used as the workpiece and WC-Co ball end mill tools with TiAlN coated were utilized in the cutting tests. Dry cutting without coolant and semi-dry cutting using botanical oil coolant were conducted and MQL(Minimum Quantity Lubricant) device was used to spray coolant. Cutting forces, tool wear and surface roughness were measured in the cutting tests. Results showed that dry cutting of KP4 and hardened STD11 specimens produced better surface quality and wear performance than MQL spray cutting did.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.238-244
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• 2004

This research conducted milling tests to study effects of cutting environment conditions of ball end milts on the characteristics of high speed milling cutting process. KP4 steels and STD11 heat treated steels were used as the workpiece and WC-Co ball end mill tools with TiAIN coated were utilized in the cutting tests. Dry cutting without coolant and semidry cutting using botanical oil coolant by the MQL(Minimum Quantity Lubricant) device were conducted. Cutting forces, tool wear and surface roughness were measured in the cutting tests. Results showed that MQL spray cutting of KP4 and hardened STD11 specimens produced better surface quality and wear performance than dry cutting did.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1998년도 제28회 추계학술대회
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• pp.221-226
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• 1998

The processing conditions for the mass production of platelet WS$_2$ lubricant powder were optimized. The mixture of tungsten and sulfur powders was sealed in a vacuum of 10$^{-3}$ torr and heat-treated at 850$\circ$C for 2 h. The internal pressure of reaction chamber was maintained at certain level by controlling the release valve automatically. The reaction product was the platelet WS$_2$ powder with an average size of 15 $\mu$m. The synthesized WS$_2$ powder was then coated on the wiper-blade of automobiles and the commercial deep-grooved ball bearing using wet and dry coating methods, respectively. High lubricity and wear resistance of wet coated wiper-blade were confirmed by the life test of 70,000 cycles. The life-time of the ball bearing assembled after WS$_2$ coating onto each part increased 50 times compared to the non-coated ball bearing.

• Tribology and Lubricants
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• 제27권2호
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• pp.88-94
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• 2011

The tribological characteristics of the swash plate surface of a compressor which is for automobile were investigated. For surface treatments, PTFE and $MoS_2$ are used as a solid lubricant, together with copper alloy. Test condition is set considering actual driving condition. Wear testing is conducted using pin on disk type tester, and the coefficient of friction and the temperature on friction surface are measured. Also, to determine the wear patterns, cross-section of friction surface is analyzed by SEM(scanning electrode microscope). The $MoS_2$, both at dry and lubricated conditions, friction surface and the coefficient of friction maintained rather stable results. But, the PTFE, at oil less condition, sample resulted in rather unstable condition. In case of copper alloy, quite higher friction coefficients(higher than 0.1) were obtained at dry condition. At the temperature of $125^{\circ}C$, seizure has occurred.