Surface Mechanical Treatment Research Articles

Complementary Machining – Machining Strategy for Surface Modification: A Review

All fabrication techniques utilized to manufacture metallic parts modify the surface integrity of the part. Complementary machining is a relatively recent machining strategy characterized by combining metal cutting and mechanical surface treatment. Typically, it implies that after conventional machining, the cutting insert is used reversely to modify the surface by local plastic deformation. To improve product performance, mechanical surface treatment is an additional phase in the manufacturing process chain that usually results in longer production times and higher costs. As a result, a variety of hybrid techniques have been created, such as complementary machining, which has the benefit of using conventional machine tools and their associated cutting tools. The study on complementary machining is reviewed in the article. The main focus is to assess the viability of complementary machining to modify surface integrity for enhanced properties by specifically establishing its effect on tool wear, surface roughness, microhardness, fatigue, microstructure, and residual stress state.

Non-Spherical Cavitation Bubbles: A Review

Cavitation is a phase-change phenomenon from the liquid to the gas phase due to an increased flow velocity. As it causes severe erosion and noise, it is harmful to hydraulic machinery such as pumps, valves, and screw propellers. However, it can be utilized for water treatment, in chemical reactors, and as a mechanical surface treatment, as radicals and impacts at the point of cavitation bubble collapse can be utilized. Mechanical surface treatment using cavitation impacts is called “cavitation peening”. Cavitation peening causes less pollution because it uses water to treat the mechanical surface. In addition, cavitation peening improves on traditional methods in terms of fatigue strength and the working life of parts in the automobile, aerospace, and medical fields. As cavitation bubbles are utilized in cavitation peening, the study of cavitation bubbles has significant value in improving this new technique. To achieve this, many numerical analyses combined with field experiments have been carried out to measure the stress caused by bubble collapse and rebound, especially when collapse occurs near a solid boundary. Understanding the mechanics of bubble collapse can help to avoid unnecessary surface damage, enabling more accurate surface preparation, and improving the stability of cavitation peening. The present study introduces three cavitation bubble types: single, cloud, and vortex cavitation bubbles. In addition, the critical parameters, governing equations, and high-speed camera images of these three cavitation bubble types are introduced to support a broader understanding of the collapse mechanism and characteristics of cavitation bubbles. Then, the results of the numerical and experimental analyses of non-spherical cavitation bubbles are summarized.

Effect of mechanical and chemical surface treatments on the repairing of milled and 3D-printed denture bases.

Ensuring a strong bond between chairside autopolymerized acrylic resin to denture base is essential for denture repair and reline procedures. However, there is no established protocol to enhance bond strength between autopolymerizing resin and computer-aided design and computer-aided manufacturing (CAD-CAM) denture base materials. The purpose of this study was to determine shear bond strength of CAD-CAM denture bases and autopolymerizing acrylic resin after mechanical and chemical surface treatments compared with heat-polymerized acrylic resin. Heat-polymerized, milled, and 3-dimensional (3D) printed denture bases were divided into 4 surface treatment protocols: none (control), airborne-particle abrasion (APA), tetrahydrofuran, and Vitacoll application. Autopolymerizing acrylic resin cylinders were bonded to denture surface. Shear bond strength and failure modes were determined after thermocycling. Denture base surfaces were assessed for surface roughness, surface morphology, and microhardness before and after surface treatment. Data was analyzed using two-way ANOVA and multiple comparison tests. The results showed that APA significantly increased shear bond strength and surface roughness of all denture base materials. Tetrahydrofuran and Vitacoll application improved shear bond strength of heat-polymerized acrylic resin, but did not reach the level achieved by APA. Conversely, tetrahydrofuran application improved bond strength of 3D-printed denture to the level of APA. Tetrahydrofuran and Vitacoll application significantly reduced denture base hardness, compared with control and APA. In conclusion, mechanical surface treatment using APA enhances the adhesion of autopolymerizing acrylic resin to heat-polymerized and CAD-CAM denture bases. Tetrahydrofuran and Vitacoll chemical surface treatment improved adhesion to heat-polymerized acrylic resin, with only tetrahydrofuran enhancing bond strength of 3D-printed denture to the level of APA. Without surface treatment, the highest bond strength was shown in 3D-printed denture base material.

SELECTION OF MATERIALS TO CREATE A MATERIAL LIBRARY IN CARUARU-PE/BRAZIL: CASE STUDY OF ORNAMENTAL STONES

This study presents the first actions and steps towards creating a Material Library, which is related to the collection of ornamental, natural and synthetic stones. The work method was designed in three stages: 1. Analysis of communication problems perceived between the design and architecture areas in an ornamental stone transformation industry in the city of Caruaru - PE/Brazil; 2. Mapping of raw materials used by the company; 3. Systematization of data based on the mechanical properties and surface treatment of ornamental stones. As a result, a collection of more than 50 samples was catalogued, which will be used for the knowledge and daily use of the general population, for the learning of students, professionals and suppliers involved in the subject of material selection.

A Comprehensive Review of Techniques for Enhancing Zirconia Bond Strength: Current Approaches and Emerging Innovations.

The increasing use of zirconia in dental restorations necessitates a comprehensive understanding of effective bonding techniques to ensure long-term clinical success. Zirconia's unique chemical composition presents challenges in achieving a durable bondas it lacks the glass phase necessary for traditional etching and silanization processes. This review evaluates current methods and emerging innovations for enhancing zirconia bond strength to resin cements. Our findings emphasize the importance of mechanical surface treatments such as air-particle abrasion and tribochemical silica-coating, which significantly improve micromechanical retention. Laser irradiation, while less commonly used, also shows promise in enhancing bond strength without compromising zirconia's structural integrity; 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) primers emerged as critical agents in forming stable P-O-Zr bonds, particularly when used with resin cements containing 10-MDP. However, variations in formulation and application methods impact their overall efficacy. Resin cement demonstrated superior bond strength compared to conventional cement, but clinical outcomes varied, highlighting the importance of cement-primer compatibility and strict procedural adherence. Emerging technologies such as polymer-infiltrated ceramic networks (PICNs) and additive manufacturing (AM) of zirconia offer potential for future advancements, although they require further research to address mechanical and aesthetic challenges. In conclusion, while established methods such as sandblasting and the use of MDP primers remain reliable, ongoing research into novel materials and techniques continues to offer opportunities for enhancing zirconia bonding. Clinicians must balance effectiveness, procedural complexity, and clinical practicality when selecting the most appropriate bonding protocols for zirconia restorations.

Comparative assessment of Ti‐6Al‐4 V titanium alloy fatigue life improvement by vibratory peening, shot peening, and vibratory finishing

AbstractThe effects of vibratory peening (VP), shot peening (SP), and SP followed by vibratory finishing (SPVF) on the surface and fatigue properties of Ti‐6Al‐4 V were compared to conventional low‐stress grinding (LSG). VP processing produced seven times smoother surface finish than SP and 66% deeper compressive residual stresses (CRS) but with 12% lower magnitudes. SPVF produced optimal surface properties with a perfectly flat surface and CRS‐like SP. All three mechanical surface treatments generated similar fatigue life improvements (108–122%) over LSG when the cyclic stress was below the yield stress. Above the yield stress, most of the CRS relaxed during the first cycle in VP specimens, resulting in up to 97% fatigue life improvement over LSG. The CRS relaxed more gradually in SP specimens leading to larger (up to 239%) fatigue life improvement. This shows the need to amplify CRS magnitudes produced in VP to maximize fatigue life improvement.

Investigation of mechanical and wettability properties of commercial pure titanium by surface mechanical attrition treatment

The examination of mechanical and wettability properties of commercial pure titanium (CP-Ti) introduced a novel challenge. The microstructure of samples was analyzed by using OM and SEM micro-images. In this study, the hardness of the surface and cross section of samples was evaluated, and the effect of several surface mechanical attrition treatments (SMATed) on samples was examined. Also, the tensile test was done to compare the effect of SMAT duration on mechanical properties of samples. The contact angle method was then employed to investigate the impact of SAMT duration on the wettability trend. According to results, as the treatment time increases, twins become evident in the deeper layers of the samples. In contrast, the near-surface twins are shorter than those found in the deeper material, signifying the presence of finer grains. Moreover, the elevated hardness in SMATed samples can be attributed to several key factors, including cold work, a rise in defects and twins, and grain refinement. The surface hardness increases across the sample series (up to Ti6) due to the substantial energy input. Nevertheless, it is anticipated that further continuation of the process will result in a constant surface hardness. The increased strength observed in SMATed samples can be attributed to factors such as reduction in grain size and the formation of twins. The wettability results show that the treated surfaces exhibited a significant change in wettability compared to the untreated samples, with a 25% reduction in the contact angle. This is attributed to the surface modifications induced by the treatment process, which introduced more hydrophilic functional groups. The results also show that after 4 h of treatment, the contact angle increases, suggesting that the trend may plateau with additional treatment time.

The Influence of Surface Nanocrystallization of TA2 Titanium Alloy on Its Corrosion Resistance

In this study, the surface nano treatment of TA2 titanium alloy was realized by means of surface mechanical wear treatment. The microstructure and electrochemical properties of the nanocrystalline layer were investigated by SEM, TEM, Electrochemical Impedance Spectroscopy, and Potentiodynamic Polarization, while the nucleation mechanism of the passivation film was discussed. The results indicate that the original coarse grains on the sample’s surface are transformed into randomly oriented nanocrystals by surface mechanical attrition treatment (SMAT). The corrosion current density of the surface nanocrystallized TA2 titanium alloy (9.2 nA·cm−2) experienced a reduction of two orders of magnitude compared to untreated TA2 titanium alloy (134.5 nA·cm−2) in 3.5 wt.% NaCl solution. The SMAT methods accelerates nucleation mechanism transitioning to continuous nucleation.

Effect of adhesives and mechanical surface treatments on the hard relining of CAD-CAM denture bases.

The aim of this study was to evaluate the impact of mechanical roughening, adhesive applications, and aging on the bonding between CAD-CAM denture base materials with distinct chemical contents and hard relining material. A total of 300 denture base specimens were produced by additive, subtractive, and conventional heat-polymerization techniques (N=100). The specimens have been classified into five subgroups based on the particular surface treatments administered (n=20): (1) Hard relining material's adhesive application (control); (2) Tungsten carbide bur application for 1min, and hard reline material's adhesive application; (3) Airborne-particle abrasion (APA) with 110 μm Al2O3, and hard reline material's adhesive application; (4) Scotchbond Universal application; and (5) Visio.link application. Representative specimens from each subgroup were examined under a Scanning Electron Microscope (SEM). Subsequently, self-cure hard relining material was condensed in the center of the specimens. Half of the specimens were thermally aged with 5000 cycles at 5°C-55°C. The shear bond strength (SBS) test was performed, and failure loads were recorded. The data was evaluated by Robust ANOVA and Bonferroni test (p<0.05). No statistically significant difference was obtained between the production techniques (p = 0.051). The lowest SBS was observed in the control group among surface treatments, while mechanical surface treatments and universal adhesive showed the highest SBS for both aged and non-aged groups. Aging caused a significant decrease for all test groups (p=0.001). Mechanical surface treatments and universal adhesive applications are more effective for maintaining adhesion across all production techniques.

Effect of Stainless Steel Substrate Preparation on the Adhesion Strength and Morphology of Electrophoretically Deposited Sodium Alginate Coatings

In this study, the influence of various mechanical and chemical surface treatments on the adhesion strength and surface properties of sodium alginate coatings electrophoretically deposited (EPD) on 316L stainless steel substrates was investigated. XPS and TEM results revealed the presence of oxide layers containing elements from the substrates, with thicknesses varying from 1 to 45 nm, depending on the treatment used. Most substrates exhibited high roughness and hydrophilic properties (CA with water 62.8–82.6 deg). Sodium alginate coatings with uniform morphology were deposited with the same process parameters, i.e., 5 V and 300 s. The surface topography of the coatings was closely related to that of the substrate on which they were deposited. All coatings exhibited higher hydrophilicity (CA with water 29.5–49.7 deg) compared to the substrates (CA with water 62.8–82.6 deg). The coatings on the etched and anodized substrates demonstrated the highest adhesion strength (class 4B), attributed to the very low oxide layer thickness and the specific substrate surface topography. Mechanical interlocking was identified as the primary adhesion mechanism for these coatings. This work provides insight into optimizing surface treatments for improved adhesion of sodium alginate coatings to stainless steel substrates widely used for temporary bone implants. The results obtained will also be helpful in providing high adhesion of sodium alginate-based composite coatings to steel substrates.

Rapid surface patterning to strengthen adhesive bonding of carbon fiber reinforced polymer by spatial shaping femtosecond laser

Carbon fiber reinforced polymer (CFRP) have become gradually important in the aerospace industry due to their outstanding strength-to-weight ratio. However, traditional mechanical surface treatment methods are challenging to apply to CFRP because of their anisotropic and nonhomogeneous properties. Femtosecond laser offers unique advantages for surface treatment, as it allows processing with very low thermal load due to the extremely short interaction time. This study investigates the effect of different surface structures resulting from surface treatment using a femtosecond laser on adhesive properties of CFRP. The experimental results show that: 1) beam shaping can be realized by using the plano-convex cylindrical mirror, which improves the quality of laser processing and greatly improves processing efficiency. It only takes 20 s to complete the laser processing of a 1 cm*1 cm area, which increases the work efficiency by 49 times. 2) pre-bonding surface treatment significantly enhances the tensile shear strength of the single lap joint, and the shear strength of samples with low spatial frequency LIPSS (LSFL) (14.57 ± 1.58 MPa) is 2.96 times higher than that of the untreated sample (US) (4.92 ± 1.34 MPa). 3) LSFL structure exhibits the best results, because the surface of CFRP with LSFL exhibits a relatively higher surface polarity and surface energy. This study provides an efficient, high-precision, and low-damage surface treatment method for preparing CFRP for adhesive bonding, which may promote the application of femtosecond laser technology in difficult-to-process composite materials and provide new methods and technical support for its application in aerospace, vehicle manufacturing, and other fields.

Effect of various surface treatment methods on shear bond strength between acrylic denture teeth and thermoplastic nylon denture base

AbstractPurposeTo evaluate the effect of mechanical, chemical, and mechanical‐chemical surface treatment methods on shear bond strength between acrylic denture teeth and thermoplastic nylon denture base.Materials and MethodsMaxillary central incisor teeth were treated with five different surface treatment methods: mechanical (sandblasting, T‐shape diatoric holes), chemical (5% acetic acid solution, bonding agent), and mechanical‐chemical (sandblasting + bonding agent) were embedded in thermoplastic nylon denture base (n = 10). A universal testing machine with a crosshead speed of 0.5 mm per minute was used to test the shear bond strength. Data obtained were statistically evaluated using one‐way ANOVA and followed with Tukey post hoc test (α = 0.05)ResultsT‐shaped diatoric holes exhibited significantly higher shear bond strength among the surface treatment groups, followed by sandblasting + bonding agent, sandblasting, bonding agent, and the acetic acid group (p &lt; 0.001)ConclusionT‐shaped diatoric holes as a mechanical surface treatment showed higher shear bond strength than other methods.

The Influence of Deep Rolling Process on Fatigue Durability for Vehicle Tie-Rod Component

In the automotive industry, most of the components are consistently subjected to the dynamic loading due to the randomly observed situations from road inputs and periodic vibration from IC engine working during the operation. Such loadings cause the durability problem which may result in failure or cracking at stresses that are well below the yield strength of the material. Therefore, along with the development of new processing techniques, different surface treatment processes are applied to enhance the fatigue behavior of components. Being one of the mechanical surface treatment methods, deep rolling is an efficient way for improvement of fatigue performance by strengthening the critical section and providing compressive type of residual stresses. In this paper, the effect of the deep rolling process on fatigue behavior of steel stud in tie-rod used as steering system component was investigated. Force-Number of cycles curves (F-N graph) for the fatigue test have been obtained from the tests. Evaluation of the fatigue endurance limits of the stud at un-rolled condition and rolled conditions at three different loads were performed. Test data was analyzed with a regression line to account for the scatter using probability density functions. The results indicate a significant enhancement in the endurance limit following the implementation of the rolling process, as compared to the unrolled state. Furthermore, it was observed that the endurance limit proportionally increased in line with the rolling load. These findings underscore the crucial role of the deep rolling process in determining the optimal rolling load for the specific stud design and material conditions.

Lithium Silicate-Based Glass Ceramics in Dentistry: A Narrative Review

Considering the rapid evolution of lithium silicate-based glass ceramics (LSCs) in dentistry, this review paper aims to present an updated overview of the recently introduced commercial novel LSCs. The clinical and in vitro English-language literature relating to the microstructure, manufacturing, strengthening, properties, surface treatments and clinical performance of LSC materials was obtained through an electronic search. Findings from relevant articles were extracted and summarised for this manuscript. There is considerable evidence supporting the mechanical and aesthetic competency of LSC variants, namely zirconia-reinforced lithium silicates and lithium–aluminium disilicates. Nonetheless, the literature assessing the biocompatibility and cytotoxicity of novel LSCs is scarce. An exploration of the chemical, mechanical and chemo-mechanical intaglio surface treatments—alternative to hydrofluoric acid etching—revealed promising adhesion performance for acid neutralisation and plasma treatment. The subtractive manufacturing methods of partially crystallised and fully crystallised LSC blocks and the additive manufacturing modalities pertaining to the fabrication of LSC dental restorations are addressed, wherein that challenges that could be encountered upon implementing novel additive manufacturing approaches using LSC print materials are highlighted. Furthermore, the short-term clinical performance of zirconia-reinforced lithium silicates and lithium–aluminium disilicates is demonstrated to be comparable to that of lithium disilicate ceramics and reveals promising potential for their long-term clinical performance.

Enhancing steel properties with surface mechanical treatments

This research presents the modification of the microstructure on the surface of a dual phase steel (DP) using three different treatments: surface mechanical attrition treatment (SMAT), surface mechanical carburizing treatment (SMCT), and surface mechanical composite coating treatment (SMCCT). We used SMAT to refine the grain size under high strain and strain rate conditions and successfully induced a phase transformation to martensite. The introduction of carbon during SMAT resulted in surface mechano-chemical carburizing, which enhanced the martensite transformation. Furthermore, the addition of silicon during the process led to the formation of SiC and Fe3C particles dispersed within the ferrite and martensite matrix, creating a surface nano-composite. Analysis using SEM and XRD revealed that the carbon and silicon-treated steel exhibited 41.4% martensite, 4.4% bainite, and 54.1% ferrite, indicating increased transformation by these elements. As a result, the alterations in the surface microstructure led to changes in the mechanical properties of the DP steel. Initially, the DP steel had Y.S. of 250 MPa and U.T.S. of 350 MPa. After SMAT treatment, its Y.S. and U.T.S. increased to 280 MPa and 380 MPa, respectively. The addition of carbon and silicon further enhanced the Y.S. and U.T.S. to 350 MPa and 450 MPa. A significant change in microhardness is achieved from 150HV0.05 to 255HV0.05 while after SMCT and SMCCT is 275HV0.05. Despite an increase in surface roughness contributing to heighten friction, there was a significant reduction in wear. This phenomenon could be attributed to grain refinement, dislocation structures, and martensite phase transformations associated with surface hardening.

Experimental investigation and numerical study on evolution of surface roughness caused by ultrasonic shot peening of 2024 aluminum alloy sheet

Ultrasonic shot peening (USP) is widely used for materials surface strengthening and metal sheet forming as a novel mechanical surface treatment technology. The USP-caused surface roughness is usually viewed as an unfavorable factor influencing the service performance of the mechanical components treated by USP. Taking advantages of the experimental investigation, analytical calculation and finite element simulation, the correlation between the USP-caused surface roughness and the USP-induced metal sheet forming deformation is studied comprehensively. Firstly, the USP intensity was experimentally tested by USP of Almen strips. In accordance with the USP intensity, the experimental investigations on the evolutions of surface roughness caused by USP of 2024 aluminum alloy sheets with the thicknesses of 1 mm, 2 mm and 3 mm were carried out, respectively. An analytical calculation model (ACM) was then proposed to account for the effects of the USP-induced metal sheet forming deformation on the USP-caused surface roughness. The analytically-calculated results are in good agreement with the experimentally-measured surface roughness caused by USP of 2024 aluminum alloy sheets. Lastly, linking the finite element simulation of the USP-induced metal sheet forming with the analytical calculation model, an innovative FEM-ACM coupling approach was presented for predicting the evolutions of surface roughness caused by USP of metal sheets. It has been experimentally validated with USP of 2024 aluminum alloy sheets, and would be of great significance for the development and industrial application of USP technology.

Influence of deep rolling at different temperatures on near-surface and mechanical properties of a Maraging C250 steel

Due to an outstanding combination of high strength and fracture toughness Maraging steels are used in numerous industries, e.g., in the aerospace sector. The high strength can be attributed to precipitation strengthening by conventional age-hardening heat treatments. However, as many of the envisaged applications will suffer from cyclic loadings, the fatigue properties are of significant interest in terms of a reliable use. Generally, Maraging steels are characterized by a relatively low fatigue strength limiting the use in certain applications. In this context, mechanical surface treatment processes are promising candidates to overcome these challenges. In particular, deep rolling represents a suitable process, as it is known for increased depth effects as well as smoother surface profiles compared to other mechanical surface treatment processes. Moreover, aging heat treatments can easily be implemented into the process. Accordingly, the present study focuses on near-surface and mechanical properties of a Maraging C250 steel after deep rolling. Characterization of the near-surface area was conducted by X-ray diffraction and hardness measurements. Mechanical properties were assessed by tensile and fatigue tests. The results presented reveal a great potential of the integration of an aging heat treatment into the deep rolling process eventually leading to significant process time reduction.

Enhancing bonding of fresh concrete to steel through Laser Surface Texturing

In this work, we investigated the adhesion between surface-treated stainless-steel samples and a standard cement mixture. Laser surface treatments such as Direct Laser Writing (DLW) and Laser-Induced Periodic Surface Structures (LIPSS) were employed, which resulted effective to reach up to 16-fold increase of adhesion compared to the untextured. A comparison with mechanical surface treatments, i.e., sandblasting, revealed that, although an increase of adhesion was achieved probably ascribable to the higher surface roughness, such improvement in terms of bonding strength was significantly lower than the one obtained with the laser surface texturing.

Enhancing surface integrity in friction stir welding through deep rolling and post-weld heat treatment

This study aimed to investigate mechanical surface treatment through deep rolling (DR) and post-weld heat treatment (PWHT) to enhance the surface integrity of an AA7075-T651 aluminum alloy welded through friction stir welding (FSW). The surface integrity of the welded joint was evaluated by analyzing residual stress, microhardness, surface roughness, microstructure, and fatigue life. The experimental design comprised three sets: one set exclusively applied FSW, another set applied FSW followed by DR (FSW-DR), and the last set applied FSW followed by PWHT (FSW-PWHT). Fatigue testing (screening) was performed through a four-point bending test with a bending stress of approximately 300 MPa, test frequency of 2.5 Hz at room temperature, and stress ratio (R) of 0. The FSW parameters included a tool rotational speed of 1600 rpm, welding speed of 30 mm/min, immersion depth of 0.1 mm, dwell time of 15 s, and tool tilt angle of 0°. The DR parameters included a rolling pressure of 150 bar and rolling speed of 1400 mm/min. The results revealed that the residual stress significantly influenced fatigue life. The fatigue test demonstrated that FSW workpieces treated with the DR process (FSW-DR) exhibited the highest fatigue life, showing a remarkable increase of 33.5 % compared with that of untreated FSW workpieces. Moreover, the residual stress changed from tensile to compressive, accompanied by noticeable enhancements in microhardness and surface roughness. These results highlight that FSW followed by the DR process (FSW-DR) positively affects weld surface integrity, resulting in an extended service life for welded components.

Simulations of the effect of shot peening backstress on nanoindentation

Shot peening is a mechanical surface treatment that can introduce compressive residual stress and work hardening simultaneously. This work hardening, considered as a modification of the elastic region with plastic strain, can be modeled with two types of contributions: isotropic hardening and kinematic hardening. In order to characterize the mechanical properties of the treated surface using the instrumented indentation technique, the effect of the backstress associated with kinematic hardening should be studied, especially for works related to fatigue loading. In this paper, the distribution of three backstress components is obtained by shot peening simulations on a nickel-based alloy, Inconel 718, commonly used in the aerospace industry, and a series of indentation simulations are carried out using a spherical tip with different equivalent backstress levels. For Inconel 718, the third backstress component, which has the slowest evolution rate, is found to have the most significant influence on the response. However, compared to the effect of residual stress and cumulated plastic strain, the effect of backstress can be neglected.