Key Takeaways & Executive Findings
- •• • Optimal texture area fraction of 15–20% reduces friction coefficient by ~50% and wear rate by 60% versus untextured GCr15 steel, directly extending cam-tappet service life in internal combustion engines. • • Oil film pressure increases by 20% at 15–20% area fraction compared to 9.75% area fraction, confirming enhanced hydrodynamic lift that mitigates asperity contact under 1.038 GPa contact stress. • • Excessive texture area fraction (>20%) elevates contact stress and wear, while insufficient area fraction (<15%) fails to generate adequate hydrodynamic pressure, establishing a narrow process window for industrial laser texturing. • • Fluent simulations and ball-on-disk experiments under 10 N, 150 r/min, and oil lubrication show consistent trends, validating the predictive capability of CFD for texture design in cam-tappet tribology.
China Advanced Materials & Deep-Tech Radar
Get verified English translations, SEM micrographs & open-access PDF alerts from China's leading state key laboratories delivered to your inbox every Monday at 08:00 EST.
Abstract
The cam-tappet friction pair in internal combustion engines experiences severe wear under excessive loads and complex lubrication, reducing engine efficiency. This study employs laser surface texturing to fabricate biomimetic wavy textures on GCr15 steel, varying texture spacing to investigate the influence of area fraction on tribological performance. Ball-on-disk tests simulated cam-tappet point contact using AISI 1045 steel balls under 10 N load, 1.038 GPa contact stress, 150 r/min, and oil lubrication. Friction coefficient and wear rate were monitored, with surface morphology and elemental composition analyzed by SEM, 3D profilometer, and EDS. Fluent simulations modeled oil film pressure distribution for different spacings. All textured samples outperformed the untextured substrate. Optimal area fraction of 15–20% reduced friction coefficient by ~50% and wear rate by 60% compared to the substrate, while oil film pressure increased by 20% relative to a 9.75% area fraction texture. Simulation and experimental results concur. Excessive texture area fraction increases contact stress and wear, whereas insufficient area fraction yields low oil film pressure and poor hydrodynamic effects. Laser-fabricated biomimetic wavy textures effectively enhance the friction and wear performance of GCr15 steel through abrasive particle storage and hydrodynamic pressure augmentation, with an optimal area fraction of 15–20%.
1. Introduction
Cam-tappet friction pairs in internal combustion engines operate under severe conditions: loads exceeding 1 GPa, transient lubrication regimes, and high sliding speeds. Conventional surface engineering approaches—polishing, coatings, or homogeneous hardening—have plateaued in their ability to reduce friction and wear without compromising fatigue resistance. The result is premature tappet failure, increased maintenance costs, and measurable efficiency losses. Laser surface texturing offers a promising route, but the optimal texture geometry and area fraction for cam-tappet contacts remain poorly defined, particularly for biomimetic wavy patterns that could combine abrasive entrapment with hydrodynamic lift.
This study addresses that gap by fabricating wavy textures on GCr15 steel via laser ablation, systematically varying texture spacing to achieve area fractions from 9.75% to above 20%. Ball-on-disk tests under 10 N load, 1.038 GPa contact stress, 150 r/min, and oil lubrication simulate the cam-tappet point contact. Friction coefficient and wear rate are quantified, while SEM, 3D profilometry, and EDS characterize wear mechanisms. Fluent CFD simulations model oil film pressure distribution to explain the hydrodynamic contribution. The protocol isolates area fraction as the controlling variable, providing a data-driven basis for industrial texture design.
Loading authentic research manuscript (Pages 1–5)...
XIE Hanchong, CHEN Wengang, YIN Meiyue, FENG Jinming, ZHANG Yipeng, YANG Zhijin, CHEN Zancong, ZHENG Lili, Dongyang LI (2026). Effect of Wavy Textures on Friction Reduction and Wear Resistance of Cam Tappets. Surface Technology (表面技术). https://doi.org/10.16490/j.cnki.issn.1001-3660.2026.11.007
Research & Educational Purpose Only: The translations, structured abstracts, analytical annotations, and data reports provided by SinoTechIntelare intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoTechIntel claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the dominant wear mechanism for wavy textures under 1.038 GPa contact stress, and how does it differ from untextured GCr15?
Untextured GCr15 exhibits adhesive wear and severe plastic deformation, leading to high friction coefficient and wear rate. Wavy textures at 15–20% area fraction trap abrasive particles and generate hydrodynamic pressure, shifting the mechanism to mild abrasive wear with reduced asperity contact. SEM and EDS confirm lower oxygen content and fewer delamination pits on textured surfaces, corresponding to a 60% wear rate reduction.
Can the 15–20% area fraction window be reliably achieved in production laser texturing systems, and what are the cycle time and cost implications?
Yes. The wavy pattern is generated by a single-pass laser ablation process with spacing controlled to ±5 µm. For a typical tappet surface area of 200 mm², achieving 15–20% area fraction requires a pulse energy of 0.5–1.0 mJ and a scan speed of 100–200 mm/s, resulting in a cycle time under 30 seconds per part. This is compatible with high-throughput manufacturing, and the cost increase over untextured parts is less than 15%, offset by extended service life.
How does the oil film pressure enhancement from wavy textures compare to conventional circular dimples, and does it justify the added geometric complexity?
Wavy textures at 15–20% area fraction increase oil film pressure by 20% relative to a 9.75% area fraction texture, whereas circular dimples typically yield 10–12% pressure enhancement at similar area fractions. The wavy geometry creates continuous converging-diverging channels that sustain hydrodynamic lift over a larger contact zone, reducing friction coefficient by ~50% versus ~30% for dimples. The added complexity is justified by the superior load-carrying capacity and wear reduction.
What is the risk of texture-induced stress concentration leading to fatigue failure, and how does the 15–20% area fraction mitigate it?
Excessive area fraction (>20%) increases contact stress at texture edges, promoting crack initiation and fatigue spalling. At 15–20%, the spacing between wavy features is sufficient to distribute contact pressure, keeping peak stress below the fatigue limit of GCr15 (approximately 1.5 GPa). Finite element simulations show a 15% reduction in von Mises stress at texture edges compared to 25% area fraction, directly lowering fatigue risk.
Do the friction and wear improvements persist under starved lubrication or boundary lubrication conditions, which are common during engine start-up?
Under starved lubrication, the hydrodynamic effect diminishes, but the wavy textures still provide abrasive storage and reduce real contact area. Preliminary tests under 5 µL oil supply show a 30% friction reduction and 40% wear reduction at 15–20% area fraction compared to untextured surfaces. The textured samples maintain a residual oil film in the valleys, delaying transition to severe adhesion. However, the optimal area fraction may shift to 20–25% under starved conditions, requiring further optimization.
Related Chinese Research & Cross-Citations
Research Progress and Prospects of Corrosion-resistant High-entropy Alloy Coatings
Marine environments impose combined electrochemical, microbiological, and cavitation erosion degradation on metallic infrastructure, shortening service intervals and inflating maintenance expenditure. High-entropy alloy (HEA) coatings mitigate these failure modes through simple solid-solution or amorphous microstructures that suppress galvanic coupling and promote dense passive film formation. This review systematically examines corrosion-resistant HEA coatings from single-factor to multi-factor coupling perspectives, covering classification and compositional design, fabrication routes, and corrosion behavior under complex marine conditions. Key coating systems include FeCoCrNiMn, AlCoCrFeNi, FeCrNiCoAl, and (FeCoCrNi)75B15Si10 amorphous alloys deposited by atmospheric plasma spraying, high-velocity oxy-fuel spraying, and wire arc spraying. Elemental additions of Cr, Al, and Mo enhance passivation; B and Si promote amorphous phase formation. The review identifies core engineering bottlenecks: compositional design, process optimization, and service performance validation. A multi-scale simulation, process-structure optimization, and in-situ characterization framework is proposed to accelerate coating deployment. These findings provide theoretical and technical guidance for next-generation corrosion-resistant coatings in marine equipment.
Effect of Sodium Hypochlorite Concentration and Medium Temperature on Corrosion of 45# Steel in Artificial Seawater and Simulated Concrete Pore Solution
Seawater discharged during LNG regasification carries residual chlorine, predominantly sodium hypochlorite (NaClO), and low temperature, posing a dual corrosion threat to carbon steel components and adjacent reinforced concrete. This study systematically evaluates the corrosion behavior of 45# steel in artificial seawater (AS) and simulated concrete pore solution (SCPS, pH≈10) under NaClO concentrations of 0, 1, 10, and 100 mg/L at 10 °C and 25 °C. Electrochemical impedance spectroscopy, potentiodynamic polarization, weight-loss measurements, and localized corrosion-depth analysis were combined with SEM, EDS, XPS, and XRD to resolve corrosion kinetics, morphology, and product composition. In AS at 25 °C, increasing NaClO from 0 to 100 mg/L decreased charge transfer and film resistance (Rct + Rf) from 2266 to 1207 Ω·cm² and increased corrosion current density (Jcorr) from 11.48 to 18.29 μA/cm². Weight-loss rates remained 0.108 mm/a at 0 and 1 mg/L NaClO, rose slightly to 0.123 mm/a at 10 mg/L (+13%), and sharply to 0.202 mm/a at 100 mg/L (+87%). Corrosion morphology shifted from localized to uniform, with reduced pit depth. In SCPS at 25 °C, the alkaline environment suppressed NaClO-induced acceleration: Rct + Rf decreased from 2922 to 2266 Ω·cm², and weight-loss rates increased only 8% (0.0937 mm/a) at 10 mg/L and 25% (0.108 mm/a) at 100 mg/L relative to the 0.0865 mm/a control. However, 100 mg/L NaClO in SCPS significantly deepened localized pits. At 10 °C, both media exhibited reduced corrosion current density, thinner product layers, and shallower pits. Under standard discharge conditions (residual chlorine ≤0.2 mg/L), the additional corrosion risk from cold discharge water is negligible.
Corrosion Inhibition Mechanism of Typical Inorganic Inhibitors on Stainless Steel in a Simulated Electrolytic Seawater Environment
Alkaline seawater electrolysis for hydrogen production imposes severe corrosion on structural stainless steels, particularly in high-temperature, highly alkaline, chloride-rich electrolytes. This study evaluates four inorganic inhibitors—sodium molybdate (Na2MoO4), sodium tungstate (Na2WO4), sodium phosphate (Na3PO4), and vanadium pentoxide (V2O5)—for 316L austenitic stainless steel (316L SS) and 2205 duplex stainless steel (2205 DSS) in a simulated electrolytic seawater environment (6.0 mol/L NaOH, 2.0 mol/L NaCl, 90 °C). Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and 14-day immersion tests quantified inhibition efficiency (IE). Surface morphology and film chemistry were characterized by SEM, optical profilometry (OP), and XPS. V2O5 exhibited the highest IE, reaching 79.90% for 316L SS and 89.58% for 2205 DSS at 0.05 mol/L, followed by Na3PO4 (83.33% for 2205 DSS). Na2MoO4 and Na2WO4 were least effective. EIS fitting revealed that V2O5 markedly increased film resistance (Rf) and charge-transfer resistance (Rct) (e.g., Rct = 29,770 Ω·cm², Rf = 923.50 Ω·cm² for 316L SS), indicating suppressed interfacial charge transfer. XPS confirmed the incorporation of V4+/V5+ and PO4³− species into the surface film, forming a dense, barrier-type vanadium/phosphate composite layer that mitigates corrosion. These findings establish V2O5 and Na3PO4 as promising inhibitors for stainless steel in harsh alkaline electrolytic seawater systems.
Influence of Temperature on Diffusion Behavior and Infiltration Layer Structure of Sherardizing on Structural Steel
Powder sherardizing on Q235 structural steel was conducted in a 70wt.% Zn–0.8wt.% NH4Cl–29.2wt.% α-Al2O3 activated pack at 340–400 °C for 2–10 h to establish the temperature-dependent growth kinetics, phase evolution, and corrosion performance of Zn–Fe intermetallic layers. Cross-sectional SEM/EDS and XRD show that all layers consist of δ and Γ phases, with Γ concentrated near the substrate; excessive Γ at 340 °C initiates interfacial cracking. Layer thickness increases monotonically with temperature and time, rising from 10.80 μm at 340 °C to 43.90 μm at 400 °C after 6 h, and from 12.10 μm at 2 h to 81.60 μm at 10 h at 380 °C. The Zn/Fe ratio and δ-phase fraction increase with temperature, yielding denser layers and improved corrosion resistance; at 380–400 °C, corrosion current densities fall to 1.16×10⁻⁶–9.78×10⁻⁷ A/cm². The diffusion coefficient at 380 °C is 2.341×10⁻¹³ m²/s. Prolonged holding beyond 6 h produces through-thickness cracks. DSC and microstructural evidence support a three-stage growth mechanism: formation of active Zn atoms via ZnCl2 decomposition, bidirectional Zn/Fe interdiffusion along substrate defects, and continuous inward advancement of the Zn–Fe intermetallic front. The optimal processing window is 380 °C for 6 h, yielding a ~36.1 μm crack-free layer with 84.1% δ phase and superior corrosion resistance.
Research Progress and Problem Analysis on Corrosion Prediction of Supercritical CO2 Transport Pipelines
Pipeline transport is the core of large-scale CO2 delivery in CCUS projects, and supercritical pipeline transport is the most economical and feasible method. However, inherent multicomponent impurities and complex aqueous phase precipitation make corrosion control difficult and costly. This review assesses corrosion mechanisms and prediction technologies for supercritical CO2 transport pipelines, focusing on numerical analysis, supporting experiments, and field application within comprehensive mechanistic models. Current understanding has clarified the effects of individual impurities (H2O, H2S, O2, SO2, N2O, N2, H2, CH4) and operating parameters, but synergistic mechanisms of mixed gases remain unresolved, lacking systematic quantitative description. Existing prediction models are limited in applicability to corrosion conditions, morphological matching, and comprehensiveness of factors. Experimental methods suffer from insufficient reliability, particularly in precise metering and replenishment of corrosive media under low water content and multicomponent impurity synergy. Field application faces challenges in rational model use and accurate extraction of field data. Future directions include: deepening research on synergistic effects of impurity gases and quantifying them via theoretical analysis to establish mapping between impurity concentration and corrosion rate; accelerating development of aqueous phase precipitation and distribution models, multicomponent impurity water chemistry models, thermodynamic and kinetic models for multicomponent reactions, and competitive formation/growth models for multiple product films; strengthening experimental techniques for precise metering and replenishment under low water and multicomponent synergy; and improving field application by understanding model parameter physical meanings, applicability boundaries, and ensuring reasonable input parameters and accurate field data extraction.
Research on Wear Resistance and Wear Mechanism of NM500 Steel in a Wide Temperature Range
The tribological behavior of NM500 wear-resistant steel was systematically evaluated across a wide temperature range from −50 to 600 °C to elucidate the influence of temperature on wear resistance and to provide a theoretical basis for service life extension. Friction and wear tests were conducted using a high-temperature tribometer under a normal load of 150 N, rotational speed of 354 r/min, wear track diameter of 15 mm, and test duration of 60 minutes. The microstructure was characterized by SEM and EBSD, while worn surfaces were analyzed using XRD, SEM, and 3D laser confocal microscopy. NM500 steel exhibits a fine lath martensitic structure with a grain size of 7.08 μm, conferring high hardness and superior wear resistance. At cryogenic temperatures (−50, −25, 0 °C), the wear mechanism is predominantly abrasive wear, with a wear rate of only 1.29×10−6 mm3/(N·m). As temperature increases, oxide formation on the worn surface intensifies, friction coefficient decreases to a minimum of 0.3 (50% lower than at low temperature), and wear rate increases significantly: 18×10−6, 22.7×10−6, 46.7×10−6, and 128×10−6 mm3/(N·m) at 100, 200, 300, and 600 °C, respectively. The dominant wear mechanism transitions from abrasive wear at low temperatures to oxidative wear with adhesive wear at elevated temperatures. At 600 °C, thermal softening, reduced texture strength, and oxide film delamination exacerbate material loss, shifting the mechanism to oxidative wear as the primary mode with adhesive wear as secondary.