Increasing Silicon Content Research Articles

Synthesis, characterization, and UV‐curing properties of silicon‐containing (Meth)acrylate monomers

AbstractEight different silicon‐containing (meth)acrylate monomers are synthesized by the substitution reaction of chlorosiloxanes with 2‐hydroxyethyl methacrylate or 2‐hydroxyethyl acrylate. Their molecular structures are confirmed by IR, 1H‐NMR, and 13C‐NMR spectroscopic analyses. The effects of silicon content on the UV‐curing behavior, physical, surface, and thermal properties are investigated. The UV‐curing behavior is analyzed by photo differential scanning calorimetry. The surface free energy of the UV‐cured film is calculated from contact angles measured using the Lewis acid‐base three liquids method. The silicon‐containing (meth)acrylate monomers perform much better than traditional (meth)acrylate monomers on UV‐curing. The silicon‐containing monomers have higher final conversions and fast UV‐curing rates in photopolymerization. The surface free energy decreases with increasing silicon content, because silicon in the soft segment is transferred to the surface, producing a UV‐cured film; this is confirmed by X‐ray photoelectron spectroscopy measurements. All these advantageous properties enable these synthetic silicon‐containing monomers to perform better in applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Molecular Dynamics Simulations of Friction Process Between Diamond-Like Carbon and Si-DLC Films

Diamond-like carbon (DLC) films have been extensively studied over the past decades due to their unique combination of properties; in particular, silicon-doped DLC (Si-DLC) films are of significant interest for tribological effects, they had a very low friction coefficient and possessed the potential to improve wear performance in humid atmospheres and at higher temperatures. But many experimental results of the Si-DLC films showed that their tribological properties changed greatly on different silicon content. In the paper, molecular dynamics (MD) simulations were used to study microstructure of amorphous Si-DLC films and a sliding friction process between DLC and Si-DLC films on un-lubricated and oil-lubricated conditions respectively. The results show that silicon atoms are almost surrounded by carbon atoms in all Si-DLC films. The sp3/sp2 ratio in Si-DLC films increases with the increasing silicon content. After sliding, a transfer film between the DLC and Si-DLC films is formed on the un-lubricated condition. In contrast, a boundary lubrication layer is found on the oil-lubricated condition. Moreover, the friction forces on the un-lubricated condition are larger than those on the oil-lubricated condition.

Efficiency in the Extraction of Pure Silicon from Al-Si Alloy Melts by a Combined Process of Solvent Refining and Centrifugation for Solar Silicon Feedstock

Solvent refining of silicon from Al-Si melts assisted by a centrifugation was investigated for three alloys in the Al-Si system. Silicon was successfully separated from aluminum-rich phase in the form of a foam by centrifugation. As the silicon content increased, the recovery decreased because less aluminum-rich phases remained in the silicon foam. The weight ratio before and after acid leaching of the silicon foam was inversely related to its apparent density before acid leaching. The purity of the extracted silicon decreased slightly with increased silicon content. The purity of the silicon flakes obtained from the Al - 30% Si alloy was 4N, except aluminum. Boron and phosphorus in the silicon flakes could be lowered effectively by decreasing the silicon content in the Al-Si alloys

Tracking the formation of vaterite particles containing aminopropyl-functionalized silsesquioxane and their structure for bone regenerative medicine.

Vaterite particles containing aminopropyl-functionalized silsesquioxane (SiV) were prepared as osteogenic devices for bone regeneration. The SixV particles (x = 0, 2.6 and 4.9 wt%) were synthesized by reacting a slurry of calcium hydroxide with carbon dioxide gas in the presence of γ-aminopropyltriethoxysilane (APTES), a source of soluble silica which would genetically enhance osteogenesis. The obtained Si2.6V and Si4.9V particles were monodispersed with a diameter of 1.4 and 1.5 μm, respectively. The Si2.6V particles showed spherical morphologies. On the surface of the Si4.9V particle small particles were aggregated, resulting in the formation of irregular textures. Transmission electron microscopy of a sectioned Si2.6V particle revealed that the vaterite particles were present as lamellae with a length of 5-20 nm and surrounded by silsesquioxane from APTES. Moreover, the vaterite lamellae were relatively orientated to the c face of the unit lattice, where it is known to be highly polarized, compared to pure vaterite, due to the exposure of the uni-ionic plane with positive (Ca2+) or negative (CO3 2-) charge. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) revealed the co-existence of amorphous calcium carbonate (ACC) in the SiV particles. On contact with physiological pH buffer solution, the vaterite was transiently stabilized and subsequently dissolved and released after the dissolution of silsesquioxane from the particles. This stabilization time was significantly increased with the increase in silicon content. The vaterite was observed in Si2.6V particles up to 3 h of soaking, which extended up to 12 h in Si4.9V particles. The formation of the particles from the precursor gel was monitored by laser Raman spectroscopy and ATR-FTIR. During the initial 1 to 2 h of the aging step, maturation of ACC into vaterite and condensation of monomeric APTES molecules were found to begin simultaneously. These reactions proceeded up to 7 h of the analysis period. The condensation of hydrolyzed APTES is suggested to occur in the vicinity of growing vaterite, which might play a role in the enclosure of vaterite in silsesquioxanes.

Analysis on Cu-WC-Si as electrode for advancement in electro-discharge machining

Selection of electrode material with high wear resistance is an important task prior to conducting electro-discharge machining (EDM). Although Copper-Tungsten electrode have high wear resistance, it is difficult to manufacture due to its variation of melting point and zero miscibility of copper (Cu) with Tungsten (W). This paper analyses the potential of Cu reinforced with tungsten carbide (WC) and silicon (Si) additive (Cu-WC-Si) as electrode material to reduce electrode wear due to erosion of copper. Cu-WC-Si was synthesised using high-energy dry ball milling with parameters such as milling time and the weight percentage of tungsten carbide and silicon as variables. Performance of Cu-WC-Si as EDM electrode was tested on machining of hardened tool steel. The result shows that the materials removal rate (MRR) increases with milling time but decreases with an increase in silicon content. Milling time also has an effect on electrode wear and surface roughness. The new Cu-WC-Si electrode material provides improvement in EDM with reduced electrode wear and good surface finish in comparison to Cu-W electrode.

Evaluation on residual stresses of silicon-doped CVD diamond films using X-ray diffraction and Raman spectroscopy

The effect of silicon doping on the residual stress of CVD diamond films is examined using both X-ray diffraction (XRD) analysis and Raman spectroscopy measurements. The examined Si-doped diamond films are deposited on WC–Co substrates in a home-made bias-enhanced HFCVD apparatus. Ethyl silicate (Si(OC2H5)4) is dissolved in acetone to obtain various Si/C mole ratio ranging from 0.1% to 1.4% in the reaction gas. Characterizations with SEM and XRD indicate increasing silicon concentration may result in grain size decreasing and diamond [110] texture becoming dominant. The residual stress values of as-deposited Si-doped diamond films are evaluated by both sin2ψ method, which measures the (220) diamond Bragg diffraction peaks using XRD, with ψ-values ranging from 0° to 45°, and Raman spectroscopy, which detects the diamond Raman peak shift from the natural diamond line at 1332 cm−1. The residual stress evolution on the silicon doping level estimated from the above two methods presents rather good agreements, exhibiting that all deposited Si-doped diamond films present compressive stress and the sample with Si/C mole ratio of 0.1% possesses the largest residual stress of ∼1.75 GPa (Raman) or ∼2.3 GPa (XRD). As the silicon doping level is up further, the residual stress reduces to a relative stable value around 1.3 GPa.

3.3 wt%C-0.1 wt%S 박육 주철의 기계적 성질에 미치는 두께, 규소 및 망간의 영향

The effects of thickness, silicon and manganese contents on the mechanical properties of 3.3 wt%C-0.1 wt%S thin-section gray cast iron plates were investigated. The eutectic cell counts and volume fraction of pearlite in the matrix decreased with increased thickness and therefore the strength and hardness decreased with it. Even though the eutectic cell count increased with increased silicon content, the volume fraction of pearlite decreased and the strength and hardness decreased with it. The pearlite was refined more with increased manganese content and therefore the strength and hardness increased with it.

Effects of strip thickness and silicon content on Magnetic Barkhausen Noise of non-oriented electrical steel at 50~Hz

Magnetic Barkhausen Noise (MBN) can be used for non-destructive evaluation of structural properties of ferromagnetic materials. An EMF due to Barkhausen noise is induced in a coil near the surface or encircling a ferromagnetic material which is subjected to an alternating external magnetic field. MBN measurements were carried out on samples of Non Grain-Oriented (NG0) steel to determine the variation with thickness and silicon content. The results show that the rms value of Barkhausen Noise (BN) amplitude increases with decreasing sample thickness and increasing silicon content. This is explained in terms of eddy current effects which increase with increasing sample thickness and reduce with increasing silicon content. Moving domain walls induce eddy currents in the sample which give rise to effective retarding pressures on the walls which in turn leads to reduced magnetic Barkhausen noise amplitude.

Proteção local, não sistêmica, do silicato de potássio reduz os sintomas da ferrugem do cafeeiro

In the first experiment, coffee plants with three pairs of leaves were sprayed with potassium silicate (K2SiO3), epoxiconazole, acibenzolar-S-methyl (ASM), and distilled water in two different ways: spraying the 3rd pair of leaves from the apex and protecting the 2nd pair of leaves or spraying the two pair of leaves on the left side of the plant and protecting the pair of leaves on the right side. After 24 h, the abaxial surface of the protected pair of leaves was inoculated with Hemileia vastatrix. In the second experiment, the 3rd pair of leaves from the apex was sprayed with K2SiO3, ASM, and distilled water and the 2nd pair of leaves was protected. At 1, 5, 15, 25, and 35 days after products application, the abaxial surface of 2nd (systemic protection) and the 3rd pair of leaves (local protection) of eight plants per treatment were inoculated with H. vastatrix. The K2SiO3 spray on the 3rd pair of leaves or on the pair of leaves on the left side was ineffective in increasing silicon concentration and also decreasing the intensity of sporulation (IE), the total number of pustules (TNP) per leaf, and rust severity on the 2nd pair of leaves or in the pair of leaves on the right side, unlike the epoxiconazole and the ASM, which exhibited systemicity in the plant. The K2SiO3 sprayed in the 3rd pair of leaves also did not guarantee, due to its non-systemic action, reduction in the IE, TNP, and rust severity compared to its local protection. The findings of this study show the possibility of using potassium silicate spray to reduce the intensity of coffee leaf rust preventively.

Chemical durability and weathering resistance of canasite based glass and glass-ceramics

Classic composition 8.4Na2O·5K2O·10.8CaO·64SiO2·10.5CaF2·1.3Al2O3 (G1/GC1) and high silicon composition 7.6Na2O·4K2O·8.4CaO·71SiO2·8CaF2·1.0Al2O3 (G2/GC2) canasite-based glass and glass-ceramics were prepared, and the chemical durability and weathering of samples were studied with XRD, ICP-AES, SEM and optical microscopy. Interestingly, a kind of color fringe pattern caused by the acid leaching was directly observed on the glass ceramic surface under optical microscopy. The 20day weight losses of glass and glass ceramic in acid (1M HCl) and alkali (1M NaOH/1M Na2CO3) solution were measured. Accelerated weathering was used to demonstrate that increasing silicon content contributes to the weathering performance of glass and glass-ceramics. For different micro-structures and compositions, the weight loss of each glass and glass-ceramic is quite different. In general, through increasing the network interconnectivity of residual glass network and suppressing the crystallization of the less durable canasite phase, the addition of SiO2 (from 60mol% to 71mol%) enhanced the chemical durability of canasite-based glass and glass ceramic relatively under acid, alkali and weathering conditions.

Crystallisation of strontium sulphates from Si-bearing aqueous solutions

The crystallisation behaviour in the SrCl2–Na2SO4–H2O system at room temperature is strongly modified by the presence of dissolved silicon. Homogeneous nucleation experiments show that silicon inhibits the formation of celestite while promoting the precipitation of SrSO4·0.5H2O and an amorphous phase. Interfacial free energies for celestite have been calculated for increasing silicon concentrations from measurements of induction times for homogeneous nucleation. The slight increase in the interfacial free energies confirms that dissolved silicon is an inhibitor of celestite nucleation. In addition, dissolved silicon has striking morphological effects. Celestite grown in the presence of silicon typically shows rounded and peanut-like morphologies formed by numerous disoriented crystals. The anomalous celestite morphologies and the increase in both induction times and interfacial free energies reveal a complex interaction between silicic acids and celestite surfaces. In situ atomic force microscopy (AFM) was used to study in detail the effect of dissolved silicon on the growth of celestite (001) faces. AFM observations show that the presence of silicon increases the growth velocity of a first monolayer on the celestite (001) face. However, once such a first monolayer is formed, no further multilayer growth is observed. Height and friction AFM images show clear differences in contrast between the first monolayer and the celestite (001) substrate, revealing differences in composition and/or structure. High-resolution AFM images of the first monolayer show patterns consistent with the celestite (001) surface lattice, indicating that a limited amount of silicon can be incorporated into the celestite structure. Therefore, both the observed inhibition of nucleation and growth of celestite and the changes in crystal morphologies can be partially related to the formation of self-limiting Si-bearing celestite monolayers.

Thermal conductivity of silicon and carbon hybrid monolayers: a molecular dynamics study

Thermal conductivities of graphene-like silicon and carbon hybrid nanostructures with silicon atom percentages varying from 0 % (graphene) to 100 % (silicene) are investigated using the reserve non-equilibrium molecular dynamic (RNEMD) method and Tersoff bond order potentials. The thermal conductivity of graphene is dramatically reduced with increasing silicon concentration, and the reduction appears to be related more to the topological structures formed than the amount of doped silicon atoms present. The reduction is collectively contributed to by reduced phonon group velocities (v), phonon free paths (l∞), and the specific heat capacity (c) of the material. For systems with high symmetry, thermal conductivity is mainly influenced by v and c. For systems with low symmetry, thermal conductivity is dominated by l∞; such materials are also more direction-dependent on thermal flux than highly symmetric materials.

Study on nanocomposite Ti–Al–Si–Cu–N films with various Si contents deposited by cathodic vacuum arc ion plating

In this study, nanocomposite Ti–Al–Si–Cu–N films were deposited on high speed steel substrates by the vacuum cathode arc ion plating (AIP) technique. By virtue of X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (FESEM), the influence of silicon content on the film microstructure and characteristics was investigated systematically, including the chemical composition, crystalline structure as well as cross-section morphologies. With increasing the silicon content, a deterioration of the preferred orientation and a dense globular structure were detected. In the meanwhile, atomic force microscopy (AFM), nano-indentation, Rockwell indenter and reciprocating test were also utilized to analyze the hardness, elastic modulus, H3/E2, friction coefficient, adhesive strength and wear rate of the Ti–Al–Si–Cu–N films. The results showed that an optimal silicon content correlated with the best mechanical and tribological properties of the presented Ti–Al–Si–Cu–N films existed. With increasing the silicon content, the hardness, elastic modulus and the ratio H3/E2 first were improved gradually, and then were impaired sharply again. When the silicon content reached to 6at.%, the film possessed the highest hardness, elastic modulus and ratio H3/E2 of approximately 24GPa, 218GPa and 0.31, respectively. Besides, films containing both 6at.% and 10at.% Si contents obtained a relatively low friction coefficient and a good adhesive strength. The wear rate decreased with an increase in hardness, with the highest hardness corresponding to a wear rate around 1.3×10−5mm3/(Nm) of the film with 6at.% Si content. The correlations between hardness and tribological properties for the films were also examined. The essence of above phenomena was attributed to the variations of microstructure and morphologies in the films induced by the increasing silicon content.

Preparation, Characterization, and Flame Retardancy of Novel Rosin-Based Siloxane Epoxy Resins

A series of novel rosin-based siloxane epoxy resins (AESE copolymers) were prepared by the reaction of ethylene glycol diglycidyl ether modified acrylpimaric acid (AP-EGDE) with poly(methylphenylsiloxane). The chemical structures of the produced epoxy resins were determined by FTIR, 1H-NMR, 13C-NMR, and epoxy equivalent weight (EEW) test. After modification, the tensile strengths of AESE (20–40) are slightly lower than that of AP-EGDE; however their breaking elongations are higher than that of AP-EGDE remarkably. TGA results reveal that the thermal stability of AESE serials is better than that of AP-EGDE due to the formation of a protective residue. The char residue of AESE increases at 700 °C with its silicon content increases. Nevertheless, there is a peak LOI value for AESE when its silicon content is 30%. Moreover, the chemical structures of char at the end of the LOI test were analyzed by FTIR. The results confirmed the formation of the protective residue.

Removal of Si from recycled aluminium alloys

Recycling of aluminium alloys is beneficial to the environment since it uses less energy than primary metal production. However, some instances, such as recycling of brazing sheets used for heat exchanger applications, lead to increased silicon content in Al–Mn alloys (3xxx series) due to the presence of clad layer of eutectic Al–Si alloy. In the present study, the removal of excess Si from recycled Al alloys has been investigated. The feasibility of removing silicon was evaluated using thermodynamic calculations. This was followed by some simple experiments by adding calcium to alloys with known silicon content to reduce it. It was found that the Si content can be reduced by 50% by this process.

Relation between microstructure and hardness of nano-composite CrN/Si3N4 coatings obtained using CrSi single target magnetron system

Sintered targets with mixed Cr and Si (10, 20, 30, 35 and 40 at. %) elemental powders were sputtered in mixture of argon and nitrogen on silicon substrates kept either at ambient temperature or at 600 °C. The microstructure was characterized using transmission electron microscopy, while mechanical properties were estimated based on hardness measurements. Observations showed that magnetron sputtering of targets with high silicon content on substrates at ambient temperature resulted in the formation of gradient nano-composites that are partly amorphous and partly crystalline. The amorphous phase dominated in the zone close to the substrate, while the nano-crystalline character was more pronounced nearer to the coating surface. The volume of crystalline phase in the coatings was decreasing with increasing silicon content to such an extent that those obtained from CrSi40 target were fully amorphous. The coatings deposited on substrates resistively heated up to 600 °C showed fine columnar microstructure with diameter decreasing with increasing silicon content, which changed to nano-composite and eventually fully amorphous for those obtained using CrSi35 and CrSi40 targets. The Elemental mapping by electron energy filtered imaging helped prove that in the nano-composite coatings the CrN–type crystalline phase and the amorphous phase are enriched respectively in chromium and silicon. The hardness of the coatings deposited at ambient temperature and characterized by mixed crystalline and amorphous microstructure was close to 20 GPa, except those containing layers enriched in chromium and silicon, which fall down to 15 GPa or even 10 GPa. The hardness of crystalline coatings deposited at 600 °C was increasing from 20 to 30–35 GPa with decreasing average column diameter from ∼40 to ∼35 and ∼25 nm (obtained from CrSi10, CrSi20 and CrSi30 targets). The higher silicon content in the coatings caused both further diminishing of the average crystallite size below 10 nm and simultaneous formation of an amorphous phase. The hardness of the coatings with such nano-composite microstructure was however decreased to ∼25 GPa. Finally, the hardness of fully amorphous coatings obtained from CrSi40 target under the same deposition conditions was at the level of 10 GPa. Our experiments proved that it is possible to obtain extremely fine columnar (Cr,Si)N coatings twice as hard as pure CrN, although a basic one target magnetron system and oxygen-contaminated CrSi targets were only used.

Shear bond strength between resin and zirconia with two different silane blends

Objective. To study in vitro the effect of two cross-linking silanes, bis-1,2-(triethoxysilyl)ethane and bis[3-(trimethoxysilyl)propyl]amine, blended with an organofunctional silane coupling agent, (3-acryloxypropyl)trimethoxysilane, on the shear bond strength between resin-composite cement and silicatized zirconia after dry storage and thermocycling. Materials and methods. Six tested groups of 90 samples of yttria stabilized zirconia were used for sample preparation. The surfaces of the zirconia were silica-coated. 3M ESPE Sil silane was used as a control. Solutions of (3-acryloxypropyl)trimethoxysilane with cross-linking silanes bis-1,2-(triethoxysilyl)ethane and bis[3-(trimethoxysilyl)propyl]amine were applied onto the surface of silicatized zirconia. 3M ESPE RelyX resin-composite cement was bonded onto the silicatized and silanized zirconia surface and light-cured. Three groups were tested under dry condition and the other three groups were tested for thermocycling. The shear bond strength was measured using a materials testing instrument. Group mean shear bond strengths were analysed by ANOVA at a significant level of p < 0.05. The zirconia surface composition was analysed by X-ray Photoelectron Spectroscopy. Results. The highest shear bond strength was 11.8 ± 3.5 MPa for (3-acryloxypropyl)trimethoxysilane blended with bis-1,2-(triethoxysilyl)ethane (dry storage). There was a significant difference between mean shear bond strength values for (3-acryloxypropyl)trimethoxysilane blended with two cross-linking silanes, bis-1,2-(triethoxysilyl)ethane and bis[3-(trimethoxysilyl)propyl]amine, after thermocycling (p < 3.9 × 10−8). Various surface treatments of zirconia influenced the surface roughness (p < 4.6 × 10−6). The chemical composition analysis showed there was an increase in silicon and oxygen content after sandblasting. Conclusions. The results suggest that the combination of functional (3-acryloxypropyl)trimethoxysilane with cross-linking bis[3-(trimethoxysilyl)propyl]amine showed superior hydrolytic stability than with bis-1,2-(triethoxysilyl)ethane.

Effect of Silicon Additions in CrSi (10, 20, 30, 40 at. % Si) Magnetron Targets on Microstructure of Reactively Deposited (Cr,Si)N Coatings

The CrSi compacts containing 10, 20, 30 and 40 at. % Si sintered from mixed elemental powders were used as targets for reactively deposited magnetron (Cr,Si)N coatings. The silicon substrates were kept either at ambient temperature or heated up to 600 °C. The microstructure observations were performed using TECNAI FEG (200 kV) with EDAX X-ray Energy Dispersive Spectroscopy (EDS) system and JEOL 3010 (300 kV) with Gatan Energy Filtering (GIF) attachment microscopes. The thin foils were cut using QUANTA Focused Ion Beam (FIB) system. The performed investigations proved that increasing silicon content in coatings deposited at 600 °C using CrSi10, CrSi20 and CrSi30 targets caused a refining of their fully crystalline CrN-type columnar microstructure from ~ 40 to ~ 35 and ~ 25 nm. The deposition performed from the same targets, but at ambient temperatures, i.e. without resistive heating of the substrates, produced coatings of mixed crystalline-amorphous type. They were characterized by gradient microstructure, i.e. amorphous material was prevailing close to the substrate and decreasing close to coating surface. The rising of silicon content in the targets resulted in decreasing amount of crystalline phase. The coatings obtained from Cr40Si target were fully amorphous independently of substrate temperature during deposition. The measurements of local chemical compositions obtained using EDS technique indicated that the Cr:Si ratio in the coatings roughly reproduced that present in the targets used for their deposition. Additionally, these measurements indicated that all coatings are contaminated with oxygen. The mapping of chemical composition using GIF technique of mixed crystalline-amorphous coatings proved that they are enriched in Cr and Si, respectively. The present results showed, that relying on single CrSi target magnetron sputtering the crystalline-amorphous nano-composite could be obtain at silicon additions from 10 to 30 at %, i.e. well above were that type of microstructure is formed during deposition using double target magnetron systems. Additionally, for the first time, the measurements helped to prove that the crystallites and amorphous material are enriched in chromium and silicon respectively, i.e. confirmed presence of CrN/Si3N4 composite.

Magnetic properties and magnetocaloric effect in La0.7Nd0.3Fe13−xSix compounds

The structural, magnetic and magnetocaloric properties in the cubic NaZn13-type La0.7Nd0.3Fe13−xSix compounds with x=1.2, 1.4, 1.6 and 1.8 are reported. All of the investigated samples are ferromagnetically ordered. The Fe saturation moment at 5K is independent of Si concentration, having a value of 2.05±0.09μB, which suggests a high degree of localization. The Curie temperatures increase almost linearly with the increase in silicon concentration. The large ΔSM values obtained for samples with low Si content are mainly due to the first-order character of the transition at TC. The field-induced transition above TC causes an asymmetric broadening of the ΔSM peak towards higher temperatures for higher applied fields. With increasing Si content, the first-order character of the transition at TC is diminished, leading to lower ΔSM values. The potential use of these materials in magnetic refrigeration is discussed.

Improvement of Rolling Contact Fatigue Life of Bearing Steel by Quenching and Partitioning Process

Over the decades, the rolling contact fatigue life of bearing steels has been enhanced mainly by the decrease in total oxygen content in the steels which was accomplished by improving steelmaking processes or facilities. However, it has almost been kept constant in the level of 5 ppm since 1990s and, therefore, it is necessary to find out other methods to enhance the RCFL. It is a well-known fact that the RCFL of bearing steels is maximized with the adequate amount of retained austenite and increasing silicon content results in the increase of the resistance to softening during tempering. In the present study, in order to take advantage of the effects of retained austenite and increasing silicon content, a new through-hardening heat treatment, quenching and partitioning (Q&amp;P), has been chosen in place of the conventional quenching and tempering. One of the distinct differences between tempering and partitioning is no fine carbide precipitation during partitioning, leading to the stabilization of retained austenite due to the diffusion of carbon atoms from martensite, which can be realized by increasing silicon content. On the other hand, the increase of silicon content retarded the spheroidization behavior of cementites, requiring higher annealing temperature to assure the complete spheroidization. A new high carbon chromium bearing steel through-hardened by Q&amp;P process showed superior RCFL characteristics to the conventional steel and process.