Type Of Surface Treatment Research Articles

A critical evaluation of bond strength tests for the assessment of bonding to Y-TZP

ObjectivesTo compare three different designs for measuring the bond strength between Y-TZP ceramic and a composite material, before and after ceramic surface treatment, evaluating the influence of the size of the adhesive interface for each design. Methods‘Macro’ tensile, microtensile, ‘macro’ shear, microshear, ‘macro’ push-out, and micropush-out tests were carried out. Two Y-TZP surface treatments were evaluated: silanization (sil) and tribochemical silica coating (30μm silica-modified Al2O3 particles+silanization) (TBS). Failure mode analysis of tested samples was also performed. ResultsBoth the surface treatment and the size of the bonded interface significantly affected the results (p=0.00). Regardless of the type of surface treatment, the microtensile and microshear tests had higher values than their equivalent “macro” tests. However, the push-out test showed the highest values for the “macro” test. The tensile tests showed the greatest variability in results. The tribochemical silica coating method significantly increased bond strength for all tests. SignificanceDifferent test designs can change the outcome for Y-TZP/cement interfaces, in terms of mean values and reliability (variability). The ‘micro’ tests expressed higher bond strengths than their equivalent ‘macro’ tests, with the exception of the push-out test (macro>micro).

Thermal conductivity of polypropylene composites filled with silane-modified hexagonal BN

The aim of this study is to increase thermal conductivity of polypropylene (PP) composites filled with hexagonal boron nitride particles. Two types of BN with different types of surface treatment were used – pristine and covered with 3-amino-propyl-3-ethoxy-silane (APTES), which was bonded to hydroxyl groups, formed on the h-BN surface by annealing at 1100 °C. The presence of covalently bonded silane functional groups on the surface of h-BN particles was proved by Fourier transform infrared spectroscopy (FTIR) method. Surface treatment of h-BN particles allowed to introduce 3-times increased amount of the filler in the composite produced by extrusion casting technique as compared with non-treated h-BN filler. The thermal conductivity of PP composites filled with surface-modified h-BN was effectively enhanced – up to 2 times as compared with the composite filled with pristine h-BN and more than 2.5–4 times as compared with pure PP.

Effect of Different Temporary Crown Materials and Surface Roughening Methods on the Shear Bond Strengths of Orthodontic Brackets

The aim of this study was to evaluate the effect of different temporary crown materials (TCMs) and surface roughening methods on the shear bond strength (SBS) of orthodontic brackets. TCMs are widely used during orthodontic treatment in teeth in need of prosthetic treatment, to prevent damage to the final restoration. However, there is no consensus considering the best method for roughening of the surface of TCMs. Five different TCMs [Dentalon Plus-(D), Basworth Trim II-(B), Voco Structure Premium-(V), 3M ESPE Protempt 4-(P), and Revotek LC-(R)] were used in this study. Different surface roughening methods (37% phosphoric acid, sandblasting, and Er:YAG laser) were employed in three subgroups (n=20). The SBS test was used to assess the durability of all groups. Scanning electron microscopy (SEM) analysis was performed on a representative specimen in each group. The highest mean SBS value was observed in group V, followed by groups D and P, regardless of the surface treatment. The lowest SBS values were observed in group B. The laser-irradiated groups had higher SBS values than the sandblasted and acid-etched groups. Furthermore, a significant difference in SBS values was observed between the laser-irradiated group V and all other groups (p<0.005). The effects of the chemical nature of TCMs on the SBS values appeared to be clinically negligible, whereas the type of surface treatments had a significant influence on bond strengths. Er:YAG laser irradiation caused a significant increase in bond strength between the TCMs and orthodontic brackets.

Measurement and correction of residual stress gradients in aeronautical gears after various induction surface hardening treatments

Surface hardening is used in the aerospace industry to increase the fatigue life of critical structural components. Processes such as induction hardening are gradually replacing traditional non-environmental friendly surface treatments. Modern induction generators allow simultaneous heating with medium and high frequencies. A large range of process parameters are then available and may be varied to obtain a given hardened depth but with different residual stress distributions. In this paper, residual stress and microhardness gradients are measured in spur gears after four different types of induction surface treatment. An accurate methodology is proposed to measure and correct XRD results for layer removal and X-ray elastic constant variations from case to core. The results indicate that induction parameters have a significant effect on the residual stresses and that the best type of treatment could be contour hardening with a significant preheating and a final dual-frequency heating. The propose methodology could be adapted for measurements in other complex parts presenting deep microstructural and residual stress gradients.

Comparative evaluation of bond strength of all-metal crowns with different luting agents after undergoing various modes of surface treatments: An in-vitro study.

Aim:This study includes a comparative evaluation of the various surface treatments of the intaglio surface of crowns in combination with various luting agents for maximal retention.Materials and Methods:Totally, 150 dies of a standard complete crown preparation were fabricated. Wax pattern with a loop on the occlusal surface was prepared on each die using standard procedures, and then crowns were cast with nickel-chromium alloy. These crowns were randomly divided into five groups as per the surface of the intaglio surface of the metal copings. The crowns in each group were again subdivided randomly into three groups as per the luting agents used resin-modified glass ionomer cement, glass ionomer cement, and zinc phosphate cement. Retention was measured (MPa) by separating the metal crowns from the metallic die under tension on a Universal testing machine.Statistical Analysis Used:The data were recorded and statistically analyzed using one-way analysis of variance followed by Tukey's test.Results:The retention differed both with surface treatment and type of luting agents. Untreated group showed the least bond strengths < sandblasting with 50 µm alumina < sandblasting with 50 µm alumina with ultrasonic cleaning < sandblasting with 110 µm alumina < sandblasting with 110 µm alumina along with ultrasonic cleaning. For luting agents, glass ionomer cement showed least bond strength because there was no chemical bonding present between metal crown and metallic die, followed by zinc phosphate cement and maximum bond strength were found for resin-modified glass ionomer cement.Conclusion:Among all types of surface treatments used in this study, maximum bond strength was yielded by sandblasting with 110 µm alumina + ultrasonic cleaning and the best luting agent was resin-modified glass ionomer cement.

Does Sandblasting Improve Bond Strength between Nano-ceramic Resin and Two Different Luting Composites?

Purpose: To assess how sandblasting influences shear bond strength (SBS) between nano-ceramic-resin and two resin cements. Methods: 40 nano-ceramic-resin blocks were divided into two groups (n=20): a control (C) and a test group (S_50) where air abrasion (50 µm, 0.28 MPa,10 s) was applied. Each group was divided into two subgroups (n=10) according to the applied luting material: a self-etch dual-cure resin cement (LP) and a dual-cure resin cement (LR). SBSs were determined with a universal testing machine at a crosshead speed of 0.5 mm/min. Fracture patterns were evaluated by a stereomicroscope (25x) and classified into adhesive, cohesive and mixed. One-way ANOVA test (α=.01) was used to establish differences between groups, considering SBS as dependent and the type of surface treatment as independent variable. Results: Mean SBS (MPa) obtained for P were 8.68 ± 1.16 for C and 13.91 ± 2.58 for S_50. Sandblasting positively affected (p<0.01) the self-adhesive cement adhesion to nano-ceramic resin. Group C_LP showed 100% of adhesive fractures, while S_50_LP had some cohesive (20%) and mixed fractures (10%). The fracture pattern of group C_LR was 60% cohesive, 20% adhesive and 20% mixed, while group S_50-LR showed 100% of cohesive failure. Conclusion: Sandblasting is suggested when luting nano-ceramic resin with LP.

Effect of the surface treatment in polyurethane and natural leather for the footwear industry

This aim of this paper is to analyse the peel strength of an adhesive joint with various types of surface treatments in order to contribute to the research and development of adhesives for the footwear industry. In the shoe industry, the adhesive properties are very important to ensure the quality of manufacture of the shoe. To better understand the behaviour of the adhesive joint, it is important to measure the peel resistance of the adhesive and use it to adjust the manufacturing process. For this work, joints were manufactured using natural leather, polyurethane (PU) and a solvent based polyurethane non structural adhesive. The influences of the application of physical surface treatments and/or primer on substrates in the peel strength of a T joint were analyzed. Several tests were used to characterize the surfaces of the substrates, including Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM) and contact angle measurements. It was found that certain surface treatments are required to obtain an adhesive joint capable of satisfying the minimum requirements of the shoes manufacturing sector.

Effect of different surface treatments on microtensile bond strength of two resin cements to aged simulated composite core materials.

Roughening of the aged composite resin core (CRC) surface seems essential for durable adhesion. The aim of this study was to investigate the influence of various surface treatments and different resin cements on microtensile bond strength (µ TBS) between two aged core build-up composites (CBCs) and feldspathic ceramic. A total of 16 composite blocks made of two CBCs, Core.it and Build-it were randomly assigned to four surface treatment groups after water storage and thermocycling (2 weeks and 500 cycles). Experimental groups included surface roughening with air abrasion (AA), hydrofluoric acid, pumice, and laser and then were bonded to computer-aided design/computer-aided manufacturing feldspathic ceramic blocks using two resin cements, Panavia F2 (PF), and Duo-link (DL). The µ TBS was tested, and the fracture mode was assessed. The data were analyzed with multiple analysis of variance to estimate the contribution of different surface treatments, resin cements, and two aged CRCs on µ TBS. Statistical significance level was set at α < 0.05. Surface treatment and cement type significantly affected bond strength (P < 0.001) but the type of CRC did not (P = 0.468). Between roughening methods, the highest and the lowest values of µ TBS were sequentially obtained in AA and Er.YAG laser groups. The highest bond strength was in AA group cemented with PF (31.83 MPa). The most common failure mode was cohesive fracture in the cement. Different surface treatments had different effects on µ TBS of aged CRCs to feldspathic ceramics. PF was significantly better than DL.

Bond Strenght of Zirconia Submitted to Different Surface Treatments

Objective: To evaluate the shear bond strength of a recent adhesive system used in the cementation of zirconia. Material and Methods: Overall, 72 zirconia specimens (Zirconzhan) were divided and randomized into 3 groups according to the type of surface treatment: G1 no treatment + adhesive system; G2 blasted with aluminum oxide + adhesive system and G3 tribochemical treatment (Rocatec Plus) + adhesive system. Half of each group (n = 12) had bond strength evaluated on two occasions: 24 hours after cementation, kept stored in distilled water at 37 ° C without thermal cycling, and after thermal cycling (5000 cycles, 5°C-55°C). Data were analyzed by ANOVA with Tukey's post-test (α≤0.05). Results: At first moment, G1 and G3 showed higher bond strength (8.64 ± 3.43 MPa and 6.55 ± 2.27 MPa) compared to G2, with no statistically significant difference between them. After thermal cycling, G3 showed higher bond strength (7.70 ± 1.82 MPa). Conclusion: Initially, only the adhesive system promoted higher bond strength, but after thermal cycling,bond strength decreased. The best treatment to promote high bond strength to zirconia is to associate tribochemical treatment with the adhesive system; most failures observed after thermal cycling were mixed and cohesive, showing a mechanical imbrication of the adhesive system, suggesting that there is no chemical bond; and the surface of the group with greater bond strength after thermal cycling showed more surface irregularities compared to the other groups.

Comparative evaluation of effect of metal primer and sandblasting on the shear bond strength between heat cured acrylic denture base resin and cobalt-chromium alloy: An in vitro study.

Aims:The aim of this study was to evaluate the effect of metal primers and sandblasting on the shear bond strength (SBS) of heat cured acrylic denture base resin to cobalt-chromium (Co-Cr) alloy.Materials and Methods:A total number of 40 disk shaped wax patterns (10 mm in diameter and 2 mm in thickness) were cast in Co-Cr alloy. Samples were divided into 4 groups depending on the surface treatment received. Group 1: No surface treatment was done and acts as control group. Group 2: Only sandblasting was done. Group 3: Only metal primer was applied. Group 4: Both metal primer and sandblasting were done. After surface treatment samples had been tested in Universal Testing Machine at crosshead speed of 0.5 mm/min in shear mode and scanning, electron microscope evaluation was done to observe the mode of failure.Statistical Analysis:All the observations obtained were analyzed statistically using software SPSS version 17; one-way analysis of variance (ANOVA) and post-hoc Tukey test were applied.Results:The one-way ANOVA indicated that SBS values varied according to type of surface treatment done. The SBS was highest (18.70 ± 1.2 MPa) when both sandblasting and metal primer was done when compared with no surface treatment (2.59 ± 0.32 MPa).Conclusions:It could be concluded that the use of metal primers along with sandblasting significantly improves the bonding of heat cured acrylic denture base resin with the Co-Cr alloy.

Analysis of the Early Stages of Osseointegration in Two Surfaces Dental Implants: Pilot Study

Objective: The aim of this article is to compare two surface treatment types of the dental implants inserted in tibiae of rabbits on the early stages of the bone repair considering the pattern of maturation of collagen fibers and the osseointegration process. Materials and methods: 10 modSAE (sandblast and acid etched modified) and 10 AO (anodic oxidation) implants were evaluated such as bone-implant contact (BIC), and collagen fiber orientation verified by circular polarized light (BICCPL). The results were measured at 7, 21 and 42 postoperative days. Results: The modSAE implants induced greater BIC at all times observed. The BICCPL analysis revealed the both implants showed a maturation pattern collagen fiber formation. However, BICCPL values of modSAE were higher than AO values at 21 days. Conclusions: In conclusion, the topography and surface characteristic of modSAE implant showed a tendency to improve bone tissue integration and also contributes to maturation of collagen fibers. This fact was evidenced at 21 days. The study shows the influence of topography and surface treatment of titanium dental implants in different stages of bone repair.

Surface treatment of concrete test specimens subjected to compression

The technological control of concrete can only be considered a quality control procedure when all its steps are followed properly. Compressive strength testing plays a critical role in the technological control of concrete structures and in the technological development of concrete. The aim of this study is to select the most suitable preparation technique for conventional and high-strength concrete by analyzing mean strength, standard deviation and coefficients of variation. Test specimens with compressive strength ranging from 20 to 120 MPa were prepared in a laboratory and were then subjected to seven different types of surface treatment, using bonded, unbonded and mechanical wear (grinding) systems. Results show that the most effective technique is grinding using a rigid head. The performance of unbonded system was also suitable for use with conventional and high strength concrete.

Effect of core surface treatment on the fracture resistance of zirconia restoration

The purpose of this study was to examine the effect of acid-base surface treatment on the fracture resistance, which is one of main mechanical property, of zirconia restoration in order to improve the bonding characterization between zirconia core and ceramic veneer in bi-layered all ceramic restoration system. 10% hydrofluoric acid (HF) and 1 M sodium hydroxide (NaOH) were used as acid and base chemical solutions for surface treatment, respectively. Fracture-resistance tests were performed to investigate the effects of acid and liner treatment on the improvement of the bonding strength between veneer ceramics and zirconia. Specimens were divided into five groups (n = 4) according to the type of surface treatment: (1) Group A, no treatment (control); (2) Group B, liner treatment; (3) Group C, 10% HF etching for 60 s; (4) Group D, 10% HF etching for 60 s and liner treatment. All results of fracture resistance test showed that there were no significant differences between surface treatment types. Failure mode observation indicated that most specimens of Cerasys, Zmatch, and ICE groups showed cohesive failure mode regardless of the method of surface treatment. From the results of study, the short (1 min) treatment of zirconia in HF solution is supposed to be suitable for improving bond strength of zirconia restoration, but long (more than 30 min) treatment of zirconia in HF solution is expected to deteriorate the zirconia structure. Also, several factors such as liner and acid treatment, which improve the fracture resistance of zirconia restoration, seemed to depend on the type of zirconia materials.

Evaluation of tensile retention of Y-TZP crowns cemented on resin composite cores: effect of the cement and Y-TZP surface conditioning.

This study evaluated the effect of the cement type (adhesive resin, self-adhesive, glass ionomer, and zinc phosphate) on the retention of crowns made of yttria-stabilized polycrystalline tetragonal zirconia (Y-TZP). Therefore, 108 freshly extracted molars were embedded in acrylic resin, perpendicular to their long axis, and prepared for full crowns: the crown preparations were removed and reconstructed using composite resin plus fiber posts with dimensions identical to the prepared dentin. The preparations were impressed using addition silicone, and Y-TZP copings were produced, which presented a special setup for the tensile testing. Cementation was performed with two adhesive resin cements (Multilink Automix, Ivoclar-Vivadent; RelyX ARC, 3M ESPE, St Paul, MN, USA), one self-adhesive resin cement (RelyX U100, 3M ESPE), one glass ionomer based cement (RelyX Luting, 3M ESPE), and one zinc phosphate cement (Cimento de Zinco, SS White, Rio de Janeiro, Brazil). For the resin cement groups, the inner surfaces of the crowns were subjected to three surface treatments: cleaning with isopropyl alcohol, tribochemical silica coating, or application of a thin low-fusing glass porcelain layer plus silanization. After 24 hours, all groups were subjected to thermocycling (6000 cycles) and included in a special device for tensile testing in a universal testing machine to test the retention of the infrastructure. After testing, the failure modes of all samples were analyzed under a stereomicroscope. The Kruskal-Wallis test showed that the surface treatment and cement type (α=0.05) affected the tensile retention results. The Multilink cement presented the highest tensile retention values, but that result was not statistically different from RelyX ARC. The surface treatment was statistically relevant only for the Multilink cement. The cement choice was shown to be more important than the crown surface treatment for cementation of a Y-TZP crown to a composite resin substrate.

Introduction of a new testing method (horizontal sorption) for thein-situanalysis of water absorption by porous stone surfaces and effect of surface treatments

The aim of this paper is to introduce the horizontal sorption technique and to demonstrate its applicability for the observation of porous materials and effect of surface treatments. The horizontal sorption testing method is a new technique, which was developed to facilitate the in-situ assessment of water absorption properties of porous materials. This new technique has some advantages compared to the already existing in-situ testing methods (Karsten pipe method, contact sponge method). It is easy to use, requires no supplementary electric devices, and tight attachment of the measuring tool onto the surface is not necessary. Moreover, the absorption of the water can be easily initiated and then documented. In the present paper several different ways of application of the technique are shown. The testing method was proven to be appropriate for the evaluation of the rate of water absorption, for determination of the sedimentary fabric of the rock (layers and orientation of the fabric results from its formation), as well as the effective depth and nature of three different types of surface treatments. These treatments were (i) organic and inorganic molecules activating bacteria in the stone, (ii) a conventional stone consolidant and (iii) a biomineralizing protective treatment. The new testing method provided valuable information about the nature of all the three treatments. Therefore the horizontal sorption method (HSM) seems to be a highly promising tool for the analysis of porous materials.

The role of microstructural characteristics in the cavitation erosion behaviour of laser melted and laser processed Nickel–Aluminium Bronze

In this study two types of laser surface treatment, laser surface melting and laser processing, were used to treat the surface of as cast Nickel–Aluminium Bronze. The two treatments were then subjected to cavitation erosion testing and were compared against as-cast Nickel–Aluminium Bronze. While the cavitation performance of the two types of laser surface treatment was equivalent, the morphology of the eroded surfaces was different. Several materials characterisation techniques including neutron diffraction for residual stress measurements and SEM were used to explain why the two eroded surfaces were different. It was found that the tensile residual stresses in the laser melted sample weakened the sample, which negated its superior strength when compared with the laser processed sample. It was also observed that the erosion and pitting in the laser melted sample were deeper and they were attributed to the tensile residual stresses accelerating the attack at grain boundaries.

Evaluation of tensile retention of Y-TZP crowns after long-term aging: effect of the core substrate and crown surface conditioning.

This study evaluated the effect of the core substrate type (dentin and composite resin) on the retention of crowns made of yttrium oxide stabilized tetragonal zirconia polycrystal (Y-TZP), submitted to three inner surface conditionings. For this purpose, 72 freshly extracted molars were embedded in acrylic resin, perpendicular to the long axis, and prepared for full crowns: 36 specimens had crown preparations in dentin; the remaining 36 teeth had the crowns removed, and crown preparations were reconstructed with composite resin plus fiber posts with dimensions identical to the prepared dentin. The preparations were impressed using addition silicone, and 72 Y-TZP copings for the tensile test were produced. Cementation was performed with a dual-cured cement containing phosphate monomers. For cementation, the crown preparation (dentin or resin) was conditioned with the adhesive system, and the ceramic was subjected to one of three surface treatments: isopropyl alcohol, tribochemical silica coating, or thin low-fusing glassy porcelain layer application plus silanization. After 24 hours, all specimens were submitted to thermocycling (6000 cycles) and placed in a special tensile testing device in a universal testing machine to determine failure loads. The failure modes of all samples were analyzed under a stereomicroscope. Two-way analysis of variance showed that the surface treatment and substrate type (α=0.05) affected the tensile retention results. The dentin substrate presented the highest tensile retention values, regardless of the surface treatment. When the substrate was resin, the tribochemical silica coating and low-fusing glaze application plus silanization groups showed the higher retention values.

Evaluation of Combined Treatments of Natural Fibers: Kenaf, Abaca and Oil Palm Fibers Using Micromechanical and SEM Methods

This paper presents the results of three different fibers, Kenaf(hibiscus cannabinus), oil palm (Elaeis guineensis) and abaca (Musa textilis) which were treated using 5 different types of surface treatments namely sodium hydroxide for 24 hours, glycidoxypropyltrimethoxy-silane for 24 hours, NaOH followed by Silane (each 24 hours), NaOH followed by Silane (each 12 hours) and NaOH followed by Silane (each 6 hours). The mechanical strength of the fibers were then studied and compared to the untreated fibers. The highest strength was given by the fibers treated with NaOH followed by the combined treatments and the lowest were the fibers treated with silane. Also the bonding strength between the fibers and unsaturated polyester resin were then evaluated using micro droplet pull out tests. It was proven that all the treatments improved on the bonding strength. The highest was silane followed by NaOH. For the combined treatments it was found that the highest IFSS was given by the lowest treatment duration at 6 hours, due to the alkali nature of NaOH corroding the fibers which were then filled with silane, thus losing the ability to properly bond with the resin. The samples were also then characterized using a SEM to check the surface morphology which revealed that the NaOH reduced the diameter by removing impurities and lignin, thus increasing the aspect ratio. While silane coats the surface, increases the diameter and reduces the aspect ratio. Keywords. Kenaf, Abaca, OPF, Chemical Treatment, Bonding Strength, Droplet Test, SEM

Microtensile bond strength of composite-to-composite repair with different surface treatments and adhesive systems

Objectives: The purpose was to investigate the effect of different surface treatments and bonding agents on the repair bond strength of different resin-based restorative materials by microtensile bond strength (μTBS) testing protocol. Materials and Methods: 24 Grandio SO(VOCO) and 24 Filtek Z250(3 M) resin composite blocks were prepared. Half of the samples (N = 12) were diamond bur-roughened and the other half (N = 12) were sandblasted by 50 μm aluminum oxide particles. They were further divided into four sub-groups (n = 3) and received the following: Sub-Group1: Adper Single Bond2 (Etch&Rinse) (3 M); Sub-Group2: Clearfil SE (Self-etch) (Kuraray); Sub-Group3: Beauty Bond (HEMA-free all-in-one) (Shofu); Sub-Group4: All Bond3 (HEMA-free, hydrophobic, etch&rinse) (Bisco). The samples were repaired by Filtek Z250 to form a block. All of the resultant sub-groups combinations consisted of one of the composite type, surface treatment type, and adhesive systems. A total of 18 groups were prepared including 2 homogeneous blocks. They were thermocycled and μTBS measurements were performed. Data were statistically analyzed with Kruskall–Wallis and Mann–Whitney U tests. Results: The experimental regroups’ μTBS reached to 34.67–66.36% and 43.44–95.52% of the cohesive bond strength for Grandio SO and Z250, respectively. The pre-existing composite type is found to be statistically important. When the surface is bur-finished Grandio performed better; when air-abrasion is considered Z250 showed higher bond strength. All-in-one adhesive system produced the weakest bond strength at all parameters. Conclusion: It may be suggested that when the pre-existing composite is unknown, air-abrasion may be performed with etch&rinse or two-step self-etch adhesives.

Microstructure and Properties of SAE 2205 Stainless Steel After Salt Bath Nitrocarburizing at 450 °C

Nitrocarburizing of the type SAE 2205 duplex stainless steel was conducted at 450 °C, using a type of salt bath chemical surface treatment, and the microstructure and properties of the nitrided surface were systematically researched. Experimental results revealed that a modified layer transformed on the surface of samples with the thickness ranging from 3 to 28 μm changed with the treatment time. After 2205 duplex stainless steel was subjected to salt bath nitriding at 450 °C for time less than 8 h, the preexisting ferrite zone in the surface transformed into austenite by active nitrogen diffusion. The main phase of the nitrided layer was the expanded austenite. When the treatment time was extended to 16 h, the preexisting ferrite zone in the expanded austenite was decomposed and transformed partially into e-nitride precipitate. When the treatment time extended to 40 h, the preexisting ferrite zone in the expanded austenite was transformed into e-nitride and CrN precipitate. Further, a large amount of nitride precipitated from preexisting austenite zone. The nitrided layer depth thickness changed intensively with the increasing nitriding time. The growth of the nitride layer takes place mainly by nitrogen diffusion according to the expected parabolic rate law. The salt bath nitriding can effectively improve the surface hardness. The maximum values measured from the treated surface are observed to be approximately 1400 HV0.1 after 8 h, which is about 3.5 times as hard as the untreated material (396 HV0.1). Low-temperature nitriding can improve the erosion/corrosion resistance. After nitriding for 4 h, the sample has the best corrosion resistance.