scholarly journals Enhancement of sp3 C Fraction in Diamond-like Carbon Coatings by Cryogenic Treatment

Coatings ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 42
Author(s):  
Jihua Peng ◽  
Jingwen Liao ◽  
Yinglong Peng ◽  
Yang Xiao ◽  
Jinhai Huang ◽  
...  

Diamond-like carbon (DLC) coatings deposited onto high-speed-steel surfaces were subjected to deep cryogenic treatment (DCT) at temperatures of −120 to −196 °C to investigate the evolution of microstructure, bonding structure, and mechanical properties. The surface morphology and the bonding structure of the DLC coatings were studied using scanning electron microscopy, transmission electron microscopy, micro-Raman spectroscopy, and X-ray photoelectron spectroscopy. It is found that DCT affects the surface morphology, especially the size and the height of the aggregates. For those DLCs with more than 50% sp3 C fraction, the sp2 C → sp3 C transformation occurred in coatings treated at a temperature of −120 to −160 °C; and the maximum fraction of sp3 C was obtained after treatment at −140 °C. Almost keeping the wear resistance of DLCs, DCT can improve the adhesion strength, and surface hardness. The findings of this study indicate that DCT will be a potential post-treatment method to tune the microstructure and mechanical performance of DLC coatings.

2020 ◽  
Vol 3 (1) ◽  
pp. 27-32
Author(s):  
Saifudin Saifudin ◽  
Wawan Purwanto ◽  
Jerry Chih Tsong Su

High Speed Steel (HSS) tool is commonly used in engineering applications, especially as cutters. The shortfall of this materials are wear and corrosion. However, these can be reduced by coating the surface of the material. Therefore, the purpose of this research is to investigate the effects of Diamond Like Carbon (DLC) coating, quenching heating treatment, and tempering on the physical and mechanical properties of HSS surface. The physical characteristics which will be investigated is the micro structure,  while the mechanical characteristics are hardness, wear and corrosion rate. HSS has variations in their chemical composition (% mass): 0.75–1.5 C,  Co >12, V > 5, 4–4.5 Cr,10–20 W and Mo. Furthermore, DLC coating uses Plasma Assisted Chemical Vapor Deposition (PACVD) technique with variation in the duration of coating (1,2,3,4,5 and 6 hours) at temperature of 300℃, with pressure variations of 1.0, 1.2, 1.4, 1.6, 1.8 and 2.0 millibar. DLC coating material be treated from methane or ethane gas, which is streamed into the fire with Argon (Ar). The result shows variations in DLC coating and the hardness grade depends on the coating time and pressure variation. DLC coating for a duration of 4 hours under 1.8 mbar pressure can reduce the surface hardness of HSS tool by 62% accompanied by increased ductility.


Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 14
Author(s):  
Jure Voglar ◽  
Živa Novak ◽  
Patricia Jovičević-Klug ◽  
Bojan Podgornik ◽  
Tadeja Kosec

The aim of the study was to evaluate the corrosion properties of three different grades of high-speed steel following a heat treatment procedure involving deep cryogenic treatment after quenching and to investigate how these properties are connected to the microstructure and hardness of the material. The hardness of steels was measured, and microstructural properties were determined through observation of the metallographically prepared steels using scanning electron microscopy. These studies were complemented corrosion evaluation by the use of corrosion potential measurement and linear polarization measurement of steels in a sodium tetraborate buffer at pH 10. The results showed that the deep cryogenic procedure of high-speed steel changed the microstructure and consequently affected the hardness of the investigated steels to different extents, depending on their chemical composition. Corrosion studies have confirmed that some high-speed steels have improved corrosion properties after deep cryogenic treatment. The most important improvement in corrosion resistance was observed for deep cryogenically treated high-speed steel EN 1.3395 (M3:2) by 31% when hardened to high hardness values and by 116% under lower hardness conditions. The test procedure for differentiating corrosion properties of differently heat-treated tool steels was established alongside the investigation.


1999 ◽  
Vol 67 (2) ◽  
pp. 163-169
Author(s):  
Takakazu TAKANO ◽  
Seichi RENGAKUJI ◽  
Susumu IKENO ◽  
Yuuko NAKAMURA ◽  
Choichiro SHIMASAKI

2005 ◽  
Vol 475-479 ◽  
pp. 3955-3958
Author(s):  
Jin Yong Xu ◽  
Yan Ping Liu ◽  
Yuan Gao ◽  
Zhong Xu

The plasma surface alloying low-alloy high speed steel (HSS) is carried out in vacuum chamber where a source electrode (W-Mo) and a work piece are properly placed. By using the sputter of glow-discharge, under the common function of electric field and temperature field, ?????? the desired alloying elements (W- Mo) are sputtered from the source cathode, traveling toward the substrate. Subsequently the alloying elements deposit onto the surface of the substrate, forming alloy diffusion layer which the depth may vary from several micron to several hundreds micron. In the end a surface low-alloy HSS steel would be produced after ultra-saturation ion carbonization. The composition of the alloyed layer is equal or similar with it of low-alloy HSS. The carbonized layer, without coarse eutectic ledeburite structure, possesses high density of finely and dispersed alloy carbides with tungsten equivalent 10% above and a significant improvement in surface hardness and wear resistance. The principle of plasma surface alloying and its test results and commercial products application are introduced in this paper.


2021 ◽  
Vol 1016 ◽  
pp. 1423-1429
Author(s):  
Kaweewat Worasaen ◽  
Andreas Stark ◽  
Karuna Tuchinda ◽  
Piyada Suwanpinij

A matrix type high speed steel YXR3 designed for a combination of wear resistance and toughness is investigated for its mechanical properties after hardening by deep cryogenic treatment follow by tempering. The deep cryogenic quenching carried out at -200 °C for 36 hours and the single step tempering results in an obvious improvement in wear resistance while balancing the toughness, comparing with the conventional quenching followed by a double tempering treatment. The quantitative image analysis reveals little difference in the MC carbide size distribution between tempering at different temperatures. The synchrotron high energy XRD confirms the MC type carbide with some evolution in its orientation together with tempered martensite approaching the BCC structure at higher temperatures. In contrary to the conventional quenching and tempering, the lowest tempering temperature at 200 °C yields a moderate drop in hardness with increase in surface toughness proportionally while exhibiting exceptional wear resistance. Such thermal cycle can be recommended for the industry both for the practicality and improved tool life.


Author(s):  
Justin L. Milner ◽  
Jeffrey A. Beers ◽  
John T. Roth

Machining is a popular and versatile manufacturing process that is widely used in today’s industry when producing metallic parts; however, limited tool life can make this an expensive and time consuming fabrication technique. Consequently, methods that decrease the rate of tool wear and, thus, increase tool longevity are a vital component when improving the efficiency of machining processes. To this end, cryogenically treating cutting tools (especially high-speed steel tooling) is becoming more commonplace since research has shown that the treated tooling exhibits significantly higher wear resistance. At this point, however, the effect of cryogenic treatments on ceramic tooling has not been established. Considering this, the research herein presents a feasibility study on the effectiveness of using cryogenic treatments to enhance the wear resistance of WG-300 whisker-reinforced ceramic cutting inserts. To begin, the effect of the cryogenic treatment on the insert’s hardness is examined. Subsequently, tool wear tests are conducted at various cutting speeds. Through this study, it is shown that cryogenically treating the ceramic inserts decreases the rate of tool wear at each of the cutting speeds that were tested. However, the degree of wear resistance introduced by cryogenically treating the inserts proved to be highly dependent on the cutting speed, with slower speeds exhibiting greater improvements. Thus, based on this initial study, the cryogenic treatment of ceramic tooling appears to produce beneficial results, potentially increasing the overall efficiency of machining processes.


1993 ◽  
Vol 8 (11) ◽  
pp. 2840-2844 ◽  
Author(s):  
Ebrahim Heidarpour ◽  
Yoshikatsu Namba

The deposition of diamond phase carbon films on stainless steel substrates by an ionized deposition technique has been studied. A molybdenum grid used during argon ion sputtering had a decisive role in improving the morphology and adhesion ability of the substrate surface. The chemical composition of the surface was obtained by x-ray photoelectron spectroscopy, indicating the reduction of oxygen, carbon, and other contamination, while the surface morphology of the substrate obtained by scanning electron microscopy showed less roughness with a partially smooth surface. Attempts to extract the deposited films from the pretreated substrate surface by a superadhesive agent with an adhesion of 250 kg/cm2 failed, yielding a much stronger adhesion for the pretreated surface. This fact was also supported by examining the surface morphology, hardness, and the resistivity of the films deposited on the same substrates. As for the crystal structure of diamond phase carbon films on stainless steel, selected area diffraction patterns obtained from transmission electron microscopy suggested a mixture of amorphous carbon and polycrystalline diamond components.


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