Temperature Rise Characteristics of Hybrid Ceramic Bearings with Steel Inner Rings
Published on:
2026-09-23 17:03
Background
Rolling bearings are critical basic components of high-end equipment. As bearing operating conditions become increasingly demanding, including high/low temperatures, wide temperature ranges, high vacuum, ultra-high speeds, strong corrosion, and intense radiation, conventional steel bearings can no longer meet the requirements of these extreme operating conditions.
Engineering ceramic materials have been widely used in applications such as CNC machine tool spindles, aircraft engines, new energy vehicles, and medical equipment due to their excellent properties, including wear resistance, resistance to high and low temperatures, high hardness, high strength, low density, low coefficient of thermal expansion, and self-lubricating properties.
Among engineering ceramics, silicon nitride demonstrates the best overall combination of properties in terms of density, elastic modulus, compressive strength, fracture toughness, and coefficient of thermal expansion. It is considered an ideal alternative to bearing steel for bearings operating in complex environments involving extremely low or extremely high temperatures.
Compared with conventional metal ball bearings, silicon nitride full ceramic ball bearings have higher material hardness and better wear resistance. Under the same operating conditions, silicon nitride full ceramic ball bearings can increase service life by 15%–20% for the same bearing type.
Because the density of silicon nitride is lower than that of bearing steel, it reduces the starting torque, rotational inertia, and centrifugal force of the bearing, thereby continuously improving the limiting speed and operating performance of the bearing.
The thermal deformation coefficient of silicon nitride is only 1/3–1/4 that of bearing steel. As a result, silicon nitride full ceramic ball bearings exhibit good thermal shock resistance under wide temperature ranges and large temperature differences. They also provide strong load-carrying capacity under high-speed operating conditions, stable operating performance, and long service life.
Full ceramic ball bearings overcome some of the limitations of metal ball bearings and hybrid ceramic ball bearings in ultra-high-speed applications. However, full ceramic bearings are often used in combination with metal shafts, and differences in physical properties place higher requirements on the fitting accuracy of the bearing.
Ceramics have high hardness, high brittleness, and a low coefficient of thermal expansion. As a result, bearing rings made of ceramic materials are not only difficult to machine, but may also crack when used in steel-based machines due to differences in thermal expansion and contraction between the ceramic and steel materials.
To avoid the problems caused by differences in material properties, this study proposes a hybrid ceramic ball bearing with a silicon nitride ceramic outer ring and ceramic balls, while the inner ring is made of bearing steel. The thermal expansion of the shaft and inner ring caused by heat generation is compensated for through clearance design, allowing the high compressive strength of the ceramic outer ring to be effectively utilized.
At present, many researchers have studied the performance of hybrid ceramic bearings. Most of these studies have focused on hybrid ceramic bearings with ceramic rolling elements and bearing steel inner and outer rings. In contrast, relatively few studies have investigated the thermomechanical characteristics of hybrid ceramic bearings in which both the rolling elements and outer ring are ceramic while the inner ring is made of bearing steel.
During operation, frictional heat generation between the individual bearing components has an important influence on bearing performance and service life. To further investigate the thermomechanical characteristics of hybrid ceramic bearings with steel inner rings (hereinafter referred to as hybrid ceramic bearings), this study establishes a mathematical model based on the properties of metal and ceramic materials to predict the temperature rise of the bearing. The model is then experimentally validated using a bearing life test machine.
Abstract
To investigate the temperature rise characteristics of hybrid ceramic bearings with steel inner rings during operation, a theoretical calculation model for the temperature rise of hybrid ceramic bearings with steel inner rings was established based on bearing thermodynamics. The model was validated using a bearing life test machine. The thermomechanical model was then used to analyze the temperature rise of the balls and raceways under different radial loads and rotational speeds.
The results show that the temperature rise of the hybrid ceramic bearing tends to stabilize after approximately 6 h of operation under load. At a constant rotational speed, the outer ring temperature increases with increasing radial load. At a rotational speed of 6 000 r/min and a radial load of 4 000 N, the maximum temperature reaches 40 ℃.
At a constant radial load, the outer ring temperature increases with increasing rotational speed. At a radial load of 1 000 N and a rotational speed of 10 000 r/min, the maximum temperature reaches 45 ℃.
The experimental temperature trend of the outer ring is generally consistent with the theoretical calculation, with a maximum error of 2.2–2.4 ℃. Simulation analysis shows that, under a certain radial load, the maximum temperature at the contact point between the ball and raceway reaches 65.61 ℃.
Conclusions
Based on bearing thermodynamics, a theoretical calculation model for heat generation in hybrid ceramic ball bearings with steel inner rings was established. The effects of load and rotational speed on bearing heat generation were analyzed using a bearing life test machine, and the theoretical calculation model was validated. A simulation model was then used to analyze the temperature variations of the balls and inner and outer rings. The following conclusions were obtained:
1) Because the thermal deformation of the steel inner ring and shaft is relatively large, while the thermal deformation of the ceramic balls and ceramic outer ring is relatively small, the bearing clearance of the hybrid ceramic bearing decreases. This reduces the available heat dissipation space and ultimately leads to an increase in temperature. Therefore, the temperature rise of the hybrid ceramic bearing is higher than that of the all-steel bearing. The temperature of the hybrid ceramic bearing tends to stabilize after 6 h of operation.
2) The operating temperature of the bearing increases with increasing load. When the load reaches 4 000 N, the temperature rises more rapidly, reaching a maximum of 40 ℃. Under no-load operation, the operating temperature remains stable at approximately 37 ℃.
3) At a constant load, the bearing temperature increases with increasing rotational speed. When the rotational speed reaches 10 000 r/min, the maximum temperature reaches 45 ℃. At rotational speeds of 6 000 and 8 000 r/min, the temperature variation is relatively stable.
4) The high-temperature region of the ball is mainly concentrated at the contact point between the ball and raceway, with a maximum temperature of 65.61 ℃. The high-temperature regions of the inner and outer rings are mainly concentrated in the raceway areas. The temperature of the inner ring raceway is approximately the same as that of the ball. However, as the load increases, the temperature difference between the ball and inner ring raceway increases. The temperature of the inner ring raceway is higher than that of the outer ring raceway, with a maximum difference of 5 ℃.
Source and Citation
This article is an English translation of the following research paper originally published in Bearing:
English citation:
TIAN J X, WU Y H, LI S H, et al. Temperature rise characteristics of hybrid ceramic bearings with steel inner rings [J]. *Bearing*, 2026 (8): 54-60. DOI: 10.19533/j.issn1000-3762.202409062.
The English version presented on this website is a translated version of the original research article. The research data, experimental results, analysis, and conclusions are derived from the original publication.
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