Lower Surface Hardness Research Articles

Simultaneous improvement of wear and corrosion resistance of microarc oxidation coatings on ZK61 Mg alloy by doping with ZrO2 nanoparticles

The poor corrosion resistance of magnesium (Mg) and its alloys limits their application in various fields. Micro arc oxidation (MAO) coatings can improve the corrosion resistance, but the pore defects and low surface hardness make them susceptible to wear and accelerated corrosion during usage. In this study, a ZrO2 nanoparticles doped-MAO coating is prepared on the ZK61 Mg alloy by utilizing an MgF2 passivation layer to prevent ablation. The ZrO2 nanoparticles re-melt and precipitate due to local discharging, which produces evenly dispersed nanocrystals in the MAO coating. As a result, the hardness of the MAO coating with the appropriate ZrO2 concentration increases by over 10 times, while the wear rate decreases and corrosion resistance increases. With increasing ZrO2 concentrations, the corrosion potentials increase from −1.528 V of the bare ZK61 Mg alloy to −1.184 V, the corrosion current density decreases from 1.065 × 10–4 A cm–2 to 3.960 × 10–8 A cm–2, and the charge transfer resistance increases from 3.41 × 102 Ω cm2 to 6.782 × 105Ω cm2. Immersion tests conducted in a salt solution for 28 d reveal minimal corrosion in contrast to severe corrosion on the untreated ZK61 Mg alloy. ZrO2 nanoparticles improve the corrosion resistance of MAO coatings by sealing pores and secondary strengthening of the corrosion product layer.

Fabrication and Tribology Properties of PTFE-Coated Cemented Carbide Under Dry Friction Conditions

PTFE coatings were deposited on YT15 carbide substrates using spray technology. A series of examinations were conducted, including the use of surface and cross-section micrographs to analyze the structural integrity of the coatings. The surface roughness, the adhesion force between the PTFE coatings and the carbide substrate, and the micro-hardness of the coated carbide were also evaluated. Additionally, the friction and wear behaviors were assessed through dry sliding friction tests against WC/Co balls. The test results indicated that while the PTFE-coated carbide exhibited a rougher surface and reduced micro-hardness, it also demonstrated a significant reduction in surface friction and adhesive wear. These findings suggest that the PTFE coatings enhance the overall wear resistance of the carbides. The lower surface hardness and shear strength of the coatings influenced the friction performance, leading to specific wear failure mechanisms, such as abrasion wear, coating delamination, and flaking. Overall, the deposition of PTFE coatings on carbide substrates presents a promising strategy to enhance their friction and wear performance. This approach not only improves the durability of carbide materials but also offers potential applications in industries where reduced friction and wear are critical for performance.

Dual-Coated Antireflective Film for Flexible and Robust Multi-Environmental Optoelectronic Applications.

Artificial antireflective nanostructured surfaces, inspired by moth eyes, effectively reduce optical losses at interfaces, offering significant advantages in enhancing optical performance in various optoelectronic applications, including solar cells, light-emitting diodes, and cameras. However, their limited flexibility and low surface hardness constrain their broader use. In this study, we introduce a universal antireflective film by integrating nanostructures on both sides of a thin polycarbonate film. One side was thinly coated with Al2O3 for its high hardness, enhancing surface durability while maintaining flexibility. The opposite side was coated with SiO2 to optimize antireflective properties, making the film suitable for diverse environments (i.e., air, water, and adhesives). This dual-coating strategy resulted in a mechanically robust and flexible antireflective film with superior optical properties in various conditions. We demonstrated the universal capabilities of our antireflective film via optical simulations and experiments with the fabricated film in different environments.

Effect of WC addition on microstructure and properties of laser melting deposited Ti6Al4V

Titanium alloys are generally characterized by low surface hardness, poor thermal conductivity, high friction coefficients and susceptibility to adhesive wear, which significantly hinder their industrial applications. To address this issue, we enhance the wear resistance of titanium alloys by incorporating nano WC particles. However, the optimal amount of WC to be added to titanium alloys remains unexplored. In this study, we prepared Ti6Al4V-xWC (wt%) (x = 0, 10, 20) coatings on Ti6Al4V substrates using laser melting deposition, specifically examining the effects of WC content on the microstructure and properties of the coating. The experimental findings indicate that the introduction of WC particles resulted in the formation of a TiC reinforced phase within the composite coating which promoted the equiaxialization of lamellae α phase. The hardness of the coatings increased significantly with the increase of the mass fraction of WC nanoparticles. Notably, the Ti6Al4V-10WC and Ti6Al4V-20WC coatings exhibited wear resistance that was 2.5 and 3.4 times greater, respectively, compared to the Ti6Al4V coatings. This enhancement in wear resistance can be attributed to the reinforcing phase (TiC) formed by the addition of WC. This experiment demonstrates a viable approach to improving the wear resistance of the Ti6Al4V titanium alloy through surface treatment.

The Impact Of Ultrasound-Assisted Mixing Method For Varnish And Components On The Varnish Layer’s Surface Hardness And Surface Scratch Resistance

The objective of this study was to determine effects of mechanical and ultrasound-assisted stirring methods for varnish + components mixing on the varnish layer’s surface hardness and surface scratch resistance. The study focused on polyurethane, acrylic, and polyester varnish systems, which were applied to three distinct wood types: Scots pine (Pinus sylvestris L.), Turkish beech (Fagus orientalis Lipsky), and African mahogany (Khaya ivorensis A. Chev.). The mixing processes included mechanical stirring for 3 and 5 minutes, as well as ultrasound-assisted stirring with varying power levels (80 watts and 120 watts) for 3 and 5 minutes. The results indicated that the highest surface hardness was achieved using the mechanical stirring method for Turkish beech with polyester varnish at 3 minutes of stirring (175.10), while the lowest surface hardness was observed for African mahogany with acrylic varnish and 120 watts ultrasound-assisted stirring for 5 minutes (66.80). The highest surface scratch resistance was observed in Scots pine treated with polyester varnish using mechanical stirring for 5 minutes (0.760 N), and in Turkish beech treated with acrylic varnish using 80 watts ultrasound-assisted stirring for 3 minutes (0.760 N). Overall, the findings suggested that the ultrasound-assisted mixing method generally fell short in terms of enhancing the varnish properties compared to the mechanical mixing technique.

Microstructure and properties of novel nano-lamellar Al27Nb18(CrZr0.5)xTi55−1.5x eutectic high-entropy alloy coatings on Ti-6Al-4V alloy

The serious wear damage caused by low surface hardness and poor wear resistance of titanium alloy severely limits its further application in engineering field. In this work, novel eutectic high entropy alloys (EHEAs) were designed by means of infinite solution strategy combined with mechanical assistance to explore the application of EHEAs in the field of surface protection coating. Three types of EHEA coatings were achieved through the adjustment of the Cr and Zr element proportions on Ti-6Al-4V alloy by laser cladding. The microstructure was eutectic structure composed of Laves and BCC/B2 phases with superlattice structure. A significant presence of stacking faults, Lomer-Cottrell locks and other defects is observed within the BCC/B2 phase, which contributes to the enhancement of both microhardness and nano-hardness. Al27Cr25Ti18Nb18Zr12 coating showed excellent wear resistance and minimal volume loss, which are 0.340 (65.38 % of the substrate) and 6.71 × 10−5 mm3/N·m (16.89 % of the substrate). Notably, the three alloys exhibit interesting selective corrosion behavior, which is mitigated by the presence of a nano-lamellar eutectic structure that limits pitting propagation.

Examination of Surface Hardness and Roughness of AISI 1050 Steel Material in Milling Based on Surface Processing Conditions

It is known that material hardness and surface conditions have a significant impact on the operating life of machine elements working with each other. In this study, Surface roughness values obtained depending on processing conditions and hardness changes on the machined surfaces during milling of AISI 1050 steel were examined. In experimental studies, ideal machining conditions were determined by taking into account surface roughness values and hardness changes using the Taguchi L18 experimental design method. In all experiments, it was observed that the lowest surface hardness was achieved under dry conditions when 6500 1/min speed, 4000 mm/min feed rate, and 0.4 mm cutting depth values were applied. When the speed increased from 5500 1/min to 6000 1/min and the feed rate increased from 4500 mm/min to 5000 mm/min, improvements in surface quality were observed in both machining conditions. In conclusion; In experiments where coolant was applied at high cutting speeds, it was determined that surface hardness and surface roughness values were higher than in dry machining conditions.

Fabrication and Tribological Properties of Diamond-like Carbon Film with Cr Doping by High-Power Impulse Magnetron Sputtering

The present study aims to investigate the advantages of diamond-like carbon (DLC) films in reducing friction and lubrication to address issues such as the low surface hardness, high friction coefficients, and poor wear resistance of titanium alloys. Cr-doped DLC films were deposited by high-power impulse magnetron sputtering (HiPIMS) in an atmosphere of a gas mixture of Ar and C2H2. The energy of the deposited particles was controlled by adjusting the target powers, and four sets of film samples with different powers (4 kW, 8 kW, 12 kW, and 16 kW) were fabricated. The results showed that with an increase in target power, the Cr content increased from 3.73 at. % to 22.65 at. %; meanwhile, the microstructure of the film evolved from an amorphous feature to a nanocomposite structure, with carbide embedded in an amorphous carbon matrix. The sp2-C bond content was also increased in films, suggesting an intensification of the film’s graphitization. The hardness of films exhibited a trend of initially increasing and then decreasing, reaching the maximum value at 12 kW. The friction coefficient and wear rate of films showed a reverse trend compared to hardness variation, namely initially decreasing and then increasing. The friction coefficient reached a minimum value of 0.14, and the wear rate was 2.50 × 10−7 (mm3)/(N·m), at 8 kW. The abrasive wear was the primary wear mechanism for films deposited at a higher target power. Therefore, by adjusting the target power parameter, it is possible to control the content of the metal and sp2/sp3 bonds in metal-doped DLC films, thereby regulating the mechanical and tribological properties of the films and providing an effective approach for addressing surface issues in titanium alloys.

Effect of Si3N4 content on microstructure and frictional-wear properties of MoNbTaWTi refractory high entropy alloy composite coatings

To address the shortcomings of the Ti-6Al-4 V alloy, characterized by low surface hardness and inadequate friction and wear properties, a composite coating of in-situ TiN reinforced MoNbTaWTi refractory high-entropy alloy was developed using laser cladding technology on Ti-6Al-4 V substrate. The effects of different Si3N4 contents on coating organization and wear resistance are discussed. Analysis through X-ray diffractometry (XRD), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA) revealed that the composite coating primarily consisted of the body-centered cubic (BCC) phase and an in-situ TiN enhanced phase. Notably, at a Si3N4 content of 2.0 wt%, the average microhardness at the coating's top surface reached 808.67 HV0.1, surpassing that of the substrate by 2.33 times. The friction coefficient was reduced to 0.3009, representing only 59.01 % of the Ti-6Al-4 V substrate. Furthermore, the wear weight loss measured at 0.4×10−2 mm3 was a mere 22.35 % of the Ti-6Al-4 V substrate, with the wear area accounting for only 0.27 % of the Ti-6Al-4 V substrate. Results demonstrated that utilizing the in-situ reaction between Ti element and Si3N4, the in-situ generated TiN reinforced phase significantly enhanced the hardness and wear resistance of the coating.

Correlation between fluoride release, surface hardness and diametral tensile strength of restorative glass ionomer cements.

The aim of this study was to determine if there is a correlation between fluoride release, surface hardness, and diametral tensile strength of restorative glass ionomer cements (GICs). Conventional (Riva Self Cure) and resin-modified (Riva Light Cure) GICs were used. Thirty-four samples (ø 6 x 3 mm) were prepared for each cement. The kinetics of fluoride release (n=4) was evaluated over 28 days using a fluoride-selective electrode (ISE 4010-C00). The analysis of surface hardness (n=10) was performed using a microhardness tester (Shimadzu HMV-2000, Japan) with a Knoop indenter and a load of 25 gf for 30 seconds. The diametral tensile strength test (n=10) was conducted on a universal testing machine at a speed of 0.75 mm/min. Fluoride release data were analyzed by two-way repeated measures ANOVA and Bonferroni post hoc test, while independent t-test was used for other analyses (α=0.05). Overall, the groups showed higher fluoride release until day 7 and a progressive decrease until day 28. On day 1 and day 21, Riva Self Cure showed a higher level of release than Riva Light Cure (p=0.026). Riva Light Cure showed higher diametral tensile strength (p<0.0001) and surface hardness (p=0.034) than Riva Self Cure. A negative correlation was found, indicating that higher fluoride release is associated with lower surface hardness and diametral tensile strength. Fluoride release and mechanical performance are related properties of GICs, and these properties exhibit different values depending on the type of material. Resin-modified GIC release less fluoride but exhibit better mechanical performance compared to conventional GIC. Key words:Diametral Tensile Strength, Fluoride, Glass Ionomer Cement, Surface Hardness.

Improving the Wear Resistance Properties of 7A04 Aluminum Alloy with Three Surface Modification Coatings

Multiple advantages, such as good formability, high specific strength, excellent thermal conductivity, and high corrosion resistance, enable aluminum alloy wide application in various fields; however, low surface hardness and poor wear resistance limit its further development. In this study, three surface modification coatings were successfully prepared on the surface of 7A04 aluminum alloy by microarc oxidation (MAO) and a combination of hard anodizing treatment (HA) and physical vapor deposition (PVD), named MAO, HA+W+DLC, and HA+Ti+ta-C, respectively. The microstructure, hardness, and tribological properties of the three coatings and the 7A04 aluminum alloy substrate were studied. The results show that the surface quality and hardness of the coated samples were higher than those of the 7A04 aluminum alloy and that the HA+Ti+ta-C coating possessed the highest hardness of 34.23 GPa. Moreover, the wear resistance of the two multilayer coatings was significantly improved during the ring-block wear tests under oil lubrication, exhibiting a wear rate of 1.51 × 10−7 mm3/N·m for HA+W+DLC and 1.36 × 10−7 mm3/N·m for HA+Ti+ta-C.

Enhanced Wear and Corrosion Resistance of AZ91 Magnesium Alloy via Adherent Si-DLC Coating with Si-Interlayer: Impact of Biasing Voltage

Magnesium alloys are the lowest-density structural metals with a wide range of applications, such as aircraft skins, engine casings and automobile hubs. However, its low surface hardness and non-corrosion resistance in natural environments limit its wide range of applications. In this work, Si-DLC coatings (Si: 15 at.%) are fabricated on AZ91 alloy using a hollow cathode discharge combined with a DC bias voltage from 0 to −300 V to increase the deposition rate and modulate the structure and properties of the coatings. The Si interlayer with a thickness of around 0.6 µm is deposited first to enhance the adhesion. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy are used to investigate the effect of DC bias on the microstructure evolution of Si-DLC coatings. Meanwhile, corrosion and wear resistance of the coatings at various bias voltages have been investigated using electrochemical workstations and pin-on-desk wear testers. It is shown that the bias-free coating has a loose structure and is less resistant to corrosion and wear. The bias coating has a compact structure, small carbon cluster size, high chloride ion corrosion resistance, and high wear resistance against Al2O3 spheres. The corrosion potential of the coating bias at −300 V is −0.98 V, the corrosion current density is 1.35 × 10−6 A·cm−2, the friction coefficient is 0.08, and the wear rate is 10−8 orders of magnitude. The formation of SiC nanocrystals and high sp3-C, as well as the formation of transfer films on the surface of their counterparts, are the main reasons for the ultra-high wear resistance of the bias coatings. The wear rate, coefficient of friction, and corrosion rate of the coating are 0.0069 times, 0.2 times, and 0.0088 times that of the AZ91 alloy, respectively. However, the bias coating has only short to medium-term protection against the magnesium alloy and no long-term protection due to cracks caused by its high internal stress.

Influence of Cold Work on the Efficiency of Vibratory Machining

The aim of the article was to determine the impact of crushed condition (work hardening) on the effectiveness of the vibratory machining. The vibratory machining processing was carried out in two steps. The first step consisted of mechanical abrasion and remove oxides from the surface of the workpieces with abrasive media. While in the second step, smoothing - polishing with metal media was performed. Vibratory polishing also strengthened the treated surfaces. The test results were compared for samples in the crushed state (work hardening, plastic processing) and samples subjected to recrystallization annealing heat treatment. Mass losses, changes in the geometric structure of the surface and changes in the hardness of the machining surfaces were analyzed. Samples subjected to recrystallization, as compared to the samples in the state after work hardening-plastic working, are characterized by a slightly higher arithmetic mean surface roughness and lower surface hardness than for analogous processes for samples not subjected to heat treatment. Heat treatment of annealing allows to remove the effects of crushing and thus it is possible to obtain larger mass losses. Smaller burrs dimensions were obtained for samples after the heat treatment – annealing than after work hardening.

Effect of multiple factors on sediment erosion characteristics of hydro turbine materials

Hydraulic turbines on sediment-laden rivers suffer from cavitation-silt erosion. This study conducted cavitation-silt erosion tests on three materials (06Cr16Ni5Mo, Q355B, 06Cr20Ni11) with different sediment concentrations and impact velocities using a rotating disk facility, and used a scanning electron microscope (SEM) to observe the cavitation-silt erosion characteristics of the materials. The results show that the cumulative weight loss of all materials continuously increases with the sediment concentration and impact velocity rises. The weight loss of 06Cr16Ni5Mo is the lowest, and 06Cr20Ni11 is the highest. As the impact velocity rises, the cumulative weight loss increases exponentially. As the sediment concentration rises, there are obvious scour marks and fatigue spalling on the material surface. As the impact velocity rises, the size and depth of micro-cutting marks and cavitation pits increases. Due to the lower surface hardness of 06Cr20Ni11, the deep platelet pits appear on the material surface.

CATHODIC PLASMA ELECTROLYTIC DEPOSITION (CPED) TECHNIQUE FOR SURFACE STRENGTHENING OF TITANIUM AND TITANIUM ALLOYS: A MINI REVIEW

Due to the unique properties of titanium (Ti) and its alloys, it has a particularly wide range of applications in aerospace, automotive, medical and other fields. However, the problems of low surface hardness, high friction coefficient and low wear resistance of Ti alloys limit its development to a certain extent. The destruction of Ti and its alloys often occurs on the surface of materials such as wear damage, corrosion, and oxidation resistance. Therefore, the exploration and application of surface strengthening technology is particularly important. The cathodic plasma electrolytic deposition (CPED) technology, as a surface modification technology, can achieve better adhesion and facilitate the material to achieve better comprehensive performance. This paper briefly introduces the basic concepts, principles and development progress of CPED. Starting from the preparation of ceramic coatings, metal coatings, diamond-like carbon films and composite coatings, it summarizes the application of CPED in Ti and its alloys. Applications in alloys to improve thermal oxidation resistance, wear resistance, corrosion resistance, and film-based adhesion. At the end, its development in the new era environment is prospected.

A Polytetrafluoroethylene@Polyacrylonitrile core-shell composite with high tribological performance

As a lubricating additive, polytetrafluoroethylene (PTFE) exhibited poor wear resistance, high wear rate and weak adhesion strength, which restricted its application in the area of lubrication and wear protection. In this paper, we prepared a PTFE-based core-shell composite (PTFE@PAN) composed of PTFE core and polyacrylonitrile (PAN) shell through an emulsion polymerization method. The PTFE core with diameter of about 80–100 nm was wrapped by the PAN shell with the thickness of about 50–60 nm. The PTFE@PAN core-shell composite present better dispersion stability in lubricating oil (poly-α-olefin 6, PAO6) than PTFE. Additionally, the PTFE@PAN composite dispersed in PAO6 exhibited significantly reduction in friction coefficient and wear scar width up to 50 % and 25 % compared to PTFE, respectively. Meanwhile, the wear volume of PTFE@PAN composite under a load of 200 N was 4.855 × 104 μm3, was merely one twenty-seventh of that of PTFE (130.6 × 104 μm3). In comparison to conventional oil lubricants, this enhanced tribological properties of PTFE@PAN composite were conducive to a homogeneous transfer film composed of the dual-phase hard polymer (PAN) and soft PTFE polymer (PTFE). Compared with PTFE, the lower surface hardness and better flexibility of PAN shell led to deformation and gap filling with the entanglement and motion of the molecular chains, which could reduce the scratches and decline the abrasive wear of the rubbing surface significantly in the course of the friction process on a rough surface under the high load. That results also suggested that the PTFE@PAN core-shell composite will be a potential lubricating and wear-resistant additive.

Microstructure Characterization and Robust Lubrication Performance of CoCrNi Medium Entropy Alloy with Advanced Electrochemical Boronizing Treatment

CoCrNi medium‐entropy alloy (MEA) is a promising material for aviation and aerospace applications due to its excellent strength and ductility. However, its low surface hardness and poor wear resistance pose challenges for its tribological performance. To address this issue, electrochemical boronizing is explored as a potential solution, offering advantages such as a fast boronizing rate and low cost. This study demonstrates that electrochemical boronizing can significantly enhance the surface hardness and self‐lubrication performance of CoCrNi MEA, as well as retain impressive mechanical performance. Results show that a boronized layer with a thickness of about 50 μm is formed on the surface in 45 min. The boronized layer is mainly composed of Co2B, Ni2B, CrB, CoB, and Ni3B. After boronizing, the surface hardness of the sample increases by about 9 times, and the ultimate tensile strength and uniform elongation can reach 97% and 73% of the original sample, respectively. Compared with the original alloy, the friction coefficient and wear rate of boronized MEA are reduced by 38% and 85% under deionized water conditions, respectively. X‐ray photoelectron spectroscopy analysis reveals the generation of boron‐containing tribofilm on the wear scars, which significantly reduces friction and wear during the friction process.

Wire-EDM cutting strategies of WC-Co hardmetals: Effect of number of EDM pass on surface integrity

In this study, the effect of the number of wire-EDM passes on the surface integrity of WC-Co hardmetals was investigated. As-received doughnut-shaped WC-25 wt%Co samples were wire EDM’ed with one, two, three and five passes. The resulting surface conditions were investigated in terms of macroscopic and microscopic examinations. Surface roughness and hardness measurements were carried out. Detailed SEM investigations were coupled with EDS analyses. Based on the experimental findings, a detailed cutting strategy was offered for WC-Co hardmetals depending on the expectations of surface conditions, production route, cost and productivity. If there is at least one subsequent process including material removal, wire-EDM with one pass is suggested to decrease cost and increase productivity. However, heat-affected zone (HAZ), recast layer and lower surface hardness region should be removed at subsequent production steps. If there are no production steps to remove HAZ, recast layer and lower surface hardness region, the number of wire-EDM passes should be maximised.

Analysis of Influencing Factors on the Tribological Behavior of 42CrMo4/17NiCrMo6-4 under Grease Lubrication.

The tribological behavior of 42CrMo4/17NiCrMo6-4 under grease lubrication was explored in terms of load, speed, hardness matching, and lubrication quantity. Optical microscopy, scanning electron microscopy, and a surface profilometer were used to investigate the wear mechanism. The results show that hardness matching has the greatest impact on the wear resistance and friction reduction of the friction pair, followed by the load factor, with the impacts of speed and lubricant quantity being minor. Increasing the hardness of 42CrMo4 reduces the friction coefficient and wear volume of the friction pair substantially. When the maximum surface hardness of 42CrMo4 was compared with the lowest surface hardness, the friction coefficient was reduced by 21.5%, and the wear volume was reduced by 87.2%. Abrasive wear is the sort of wear failure that was seen, and as the hardness of 42CrMo4 increased, more severe fatigue wear appeared on 17NiCrMo6-4. While the wear volume initially increases and subsequently lowers with increasing load, the friction coefficient initially decreases and then stabilizes. A synergistic combination of abrasive and adhesive wear occurs under high load, changing the wear type from abrasive wear under low load. The wear volume is decreased by the sticky layer generated under high load conditions, which achieves superior wear prevention. This study is anticipated to offer recommendations for designing gears' required hardness under various operating circumstances.

Comparison of Marginal Adaptation, Surface Hardness and Bond Strength of Resected and Retrofilled Calcium Silicate-based Cements Used in Endodontic Surgery: An In Vitro Study.

This study compared the effects of orthograde and retrograde methods on marginal adaptation, surface hardness, and push-out bond strength (POBS) of three calcium silicate-based used in endodontic surgery. Ninety single-rooted human mandibular premolars were randomly assigned into six groups (n = 15/group): groups I and II, ProRoot mineral trioxide aggregate (MTA) with orthograde and retrograde methods; groups III and IV, Biodentine (BD) with orthograde and retrograde methods; groups V and VI, iRoot BP Plus (BP-RPM) with orthograde and retrograde methods. After obturation, the apical 3 mm of each root was sectioned into two 1-mm-thick root slices and evaluated for marginal adaptation using a scanning electron microscope, surface hardness using Vickers hardness tester and POBS using a universal testing machine. Orthograde placement had a higher maximum gap width than retrograde placement (p < 0.05), but there was no significant difference among the tested materials (p > 0.05). Biodentine exhibited lower surface hardness than ProRoot MTA and iRoot BP Plus (p < 0.05), but there was no significant difference between ProRoot MTA and iRoot BP Plus (p > 0.05). Orthograde placement had higher POBS compared with retrograde placement (p < 0.05). Biodentine had higher POBS than iRoot BP Plus (p < 0.05), but no significant difference from ProRoot MTA (p > 0.05). The failure mode was mainly mixed for all the tested materials regardless of material type or placement technique. The retrograde method had better marginal adaptation; however, the orthograde method provided better dislodgement resistance. Biodentine had lower surface hardness than MTA and iRoot BP Plus with both techniques, whereas iRoot BP Plus demonstrated lower dislodging resistance than BD. The current findings suggest that orthograde technique, a simpler periapical surgery, with ProRoot MTA provides potentially better surface hardness and POBS than BD and iRoot BP Plus in single-canal teeth.