•Borided AISI H13 steels were evaluated by the scratch test.•Influence of indenter tip radius on failure mechanisms was studied.•The smaller indenter tip radius generated more severe damage.
In this ...work, the influence of indenter tip radius (ITR) on scratch tests in boride layers was studied. The thermochemical treatment of boriding was performed on an AISI H13 steel at 1000 °C for 1 h. Depth sensing indentation test was developed to estimate both, hardness, and elastic modulus of the boride-layer/substrate system. Indenter radius of 200, 100, 50 and 20 μm were used for the scratch tests on borided steel. Failure mechanisms were analyzed by scanning electron microscopy (SEM). Predominant failure mechanisms were lateral cracking, chipping, and gross chipping. ITR of 20 μm developed more severe damage on the borided AISI H13 surface and the more severe substrate plastic deformation was obtained by ITR of 200 μm.
The boriding process is a branch of materials heating treatments that studies the improvement of the mechanical properties in steels and alloys. Recently, the borided trends have been studied by a ...selected group of researchers around the world with an interest to divulge the new results on borided materials for different industrial and biomedical applications. The aim of this study is to provide an overview of the historical review of the boriding process using the Bibliometric analysis. In total, 1227 documents in the Scopus database have used the boriding process as keyword with a growth rate of 7.3% every year from 1962 to 2020. The papers were written by around 2434 authors, mainly from Mexico, Turkey, and Poland, representing 37.7% of the total publications analyzed. The data obtained show that the boriding process has been global and fast-growing in the scientific publications of the last ten years.
Graphic Abstract
New results about the evolution of the FeB-Fe2B layers during a diffusion annealing process (DAP) are presented in this work. First, the growth of the boride layers over the surface of an AISI 1045 ...steel was developed by means of the powder-pack boriding process (PPBP) at temperatures of 1173–1273K with different exposure times for each temperature. The boron diffusion coefficients in the FeB and Fe2B were estimated according to the mass balance equations on the growth interphases, and expressed as a function of the boriding temperatures by the Arrhenius equation. Moreover, the DAP was conducted on borided samples obtained at 1273K with 4–8h of exposure using a SiC atmosphere, and considering the theoretical values of annealing times proposed by the extended model. The evolution of the boride layer microstructure was represented by the interphase velocities of the FeB/Fe2B and Fe2B/substrate, and the relationships between the growth of the Fe2B at the expense of the FeB layer for the applied range of annealing times.
•Borided steels were exposed to an annealing process using a SiC atmosphere.•Annealing times were proposed based on the growth kinetics of boride layer.•A complete elimination of the FeB layer was observed after the annealing process.•Kinetic expressions were obtained for the boride layer evolution during annealing.
In this work, an experimental-numerical evaluation of the standing contact fatigue testing of a nitrided AISI 316L steel was developed. The nitride layers were formed at the surface of an AISI 316L ...steel by a salt bath nitriding process at a temperature of 580 °C for 1, 3 and 5 h of exposure time, obtaining three different layer thicknesses. In order to know the mechanical response and the different mechanisms of damage associated with the standing contact fatigue test, Hertzian tests were performed on a MTS machine by cyclic loading of a sphere on a flat surface formed by the layer/substrate system. The standing contact fatigue test was developed through two main stages. First, the critical loads for each treatment condition were determined by monotonic tests, where the appearance of circular cracks was considered as the failure criterion. Subsequently, cyclic subcritical loads were applied at a frequency of 5 Hz. A numerical model based on the finite element method was developed to evaluate the stress field generated in the system by cyclic contact loads. The results indicate that the thinnest thickness of nitride layer exhibits better resistance to standing contact fatigue.
•Nitride layers were evaluated through standing contact fatigue.•The stress field associated with contact damage modes in the nitride layers was obtained by the finite element method.•Cohesive damage was a function of both the range of the maximum principal stress and the amplitude of the radial distance.
This study evaluated the influence of the TiO2 nanoparticles (NPs) on the mechanical and chemical performance of Sn and Sn–Ag alloys. The XRD (X-ray diffraction) and HR-TEM (high ...resolution-transmission electron microscopy) methods were used to characterize the NPs synthesized by the sol-gel microwave process. The chemical composition of the alloys was Sn, Sn+3TiO2 NPs, Sn–5Ag+1.5TiO2 NPs, Sn–10Ag, and Sn–10Ag+3TiO2 NPs, obtained from an experimental factorial design (EFD). A statistical model was used to determine the mechanical and chemical properties, showing the Vickers hardness response surface, tensile strength, wear, and corrosion resistance. The wear and corrosion tests for the various alloy compositions were performed using human artificial saliva solution. The results indicated that the Sn–10Ag+3TiO2 NPs exhibited the highest mechanical performance due to their increased hardness (380 HV), tensile strength (370 N), and wear resistance (0.34 × 10−3 mm3 Nm−1); in all the cases, the inclusion of TiO2 NPs enhanced the corrosion resistance of the alloys. According to the American Dental Association (ADA), Sn–10Ag+3TiO2 NPs alloy could be classified as a possible type IV restorative material.
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•The sol-gel microwave method was successfully used for the synthesis of TiO2 NPs.•The addition of TiO2 NPs modified the microstructure Sn–Ag alloys.•The addition of TiO2 NPs enhanced hardness and wear performance of the Sn–Ag alloy.•The TiO2 NPs remarkably increased the corrosion resistance of Sn–Ag alloy.•According to the results, Sn–Ag + NPs might be reclassified as ADA type IV material.
Characterization of AISI 4140 borided steels Campos-Silva, I.; Ortiz-Domínguez, M.; López-Perrusquia, N. ...
Applied surface science,
02/2010, Letnik:
256, Številka:
8
Journal Article
Recenzirano
Odprti dostop
The present study characterizes the surface of AISI 4140 steels exposed to the paste-boriding process. The formation of Fe
2B hard coatings was obtained in the temperature range 1123–1273
K with ...different exposure times, using a 4
mm thick layer of boron carbide paste over the material surface. First, the growth kinetics of boride layers at the surface of AISI 4140 steels was evaluated. Second, the presence and distribution of alloying elements on the Fe
2B phase was measured using the Glow Discharge Optical Emission Spectrometry (GDOES) technique. Further, thermal residual stresses produced on the borided phase were evaluated by X-ray diffraction (XRD) analysis. The fracture toughness of the iron boride layer of the AISI 4140 borided steels was estimated using a Vickers microindentation induced-fracture testing at a constant distance of 25
μm from the surface. The force criterion of fracture toughness was determined from the extent of brittle cracks, both parallel and perpendicular to the surface, originating at the tips of an indenter impression. The fracture toughness values obtained by the Palmqvist crack model are expressed in the form
K
C
(
π/2)
>
K
C
>
K
C
(0) for the different applied loads and experimental parameters of the boriding process.
In this study, the fracture toughness of boride coatings formed at the surface of AISI 1045 steel was improved by means of a diffusion annealing process. First, the boriding of AISI 1045 steel was ...performed by the powder-pack method at a temperature of 1223K and a range of exposure times (8–12h). The diffusion annealing process was conducted on the borided steels at a temperature of 1273K with 8h of exposure using a diluent atmosphere of SiC powder and bentonite. To establish the mechanical behavior of the boride coatings developed by both treatments, properties such as the real hardness and the Young's modulus were estimated at 50μm from the surface using Vickers and Knoop testing, respectively. The fracture toughness of the boride coatings was estimated using a universal crack equation applicable independently of the cracking mode. The boride coating obtained by the boriding process exhibited an intermediate cracking mode, while the coatings obtained by the diffusion annealing process showed a radial-median mode.
The effect of the diffusion annealing process on the fracture toughness of the boride coatings revealed an increase of approximately 50% in comparison with the coatings developed by the powder-pack boriding process.
•A homogenizing process increased the fracture behavior of the boride coating.•The fracture toughness was estimated with a universal crack equation.•Two different cracking modes were evaluated in the boride coating.
New results about the tribocorrosion resistance of borided ASTM F1537 alloy immersed in Hank's solution were obtained in this study. A CoB-Co2B layer, with around 30 μm of thickness, was obtained at ...the surface of the cobalt-based alloy using the powder-pack boriding process at 1273 K with 6 h of exposure. The tribocorrosion tests were carried out in the borided ASTM F1537 alloy and the non-borided ASTM F1537 alloy (reference material) using a linear reciprocating tribometer coupled with a standard three-electrode electrochemical cell. A counterpart of alumina (ball of 4.8 mm-diameter) was used, with a constant applied load of 20 N, and a total sliding distance of 100 m. The total material loss rate due to tribocorrosion (T), which included the mass loss rate due to wear (W) and that due to corrosion (C), was estimated according to the ASTM G119 procedure.
The results showed that the presence of CoB-Co2B layer at the surface of the ASTM F1537 alloy increased the tribocorrosion resistance around 1.2 times compared with the reference material. In addition, for the reference material, 55% of the material loss rate was attributed to the wear-corrosion synergism in comparison with 47% estimated for the borided ASTM F1537 alloy. Finally, the influence of wear affected in greater extent than corrosion in the reference material, whilst the corrosion-wear regime was obtained for the borided ASTM F1537 alloy.
•New results about the tribocorrosion behavior of the CoB-Co2B layer were obtained.•The tribocorrosion resistance was enhanced by the presence of the CoB-Co2B layer.•47% of the total material loss rate was attributed to the corrosion-wear synergism.•A corrosion-wear regime was obtained for the borided ASTM F1537 alloy.
This work presents an experimental-numerical study on the resistance of cobalt borides (CoB/Co2B) to contact fatigue. The boride layers were formed at the surface of a CoCrMo alloy using the ...powder-pack boriding process at temperatures of 1123 K for 3 h and 1223 K for 1 and 5 h of exposure times, in order to obtain three different thicknesses. The contact fatigue tests were performed with a servo-hydraulic universal testing machine by cyclic loading of a sphere on the layer-substrate system. The methodology of the contact fatigue test consisted of two main stages. Firstly, a critical load under monotonic loading was determined, where circular cracks were considered as the failure criterion. Secondly, fatigue conditions were conducted in low-cycle using sub-critical monotonic loads with a frequency of 6 Hz. A comparison of the results showed differences in the characteristics of the hard coating degradation in each case. The stress affiliated to the contact damage modes in the coating was obtained by the finite element method. The results of this study showed that contact damage modes in cyclic loading with sphere in cobalt boride coatings were a function of the coating thickness, number of cycles and contact load.
•Cobalt boride layers were evaluated through standing contact fatigue.•Stresses affiliated to contact damage modes in the coating were obtained by the finite element method.•Contact damage modes in cyclic loading were function of layer thicknesses.
New fracture toughness (KC) data for cobalt boride (CoB and Co2B) coatings were obtained using the Vickers depth-sensing microindentation technique. The coatings were developed on the surface of a ...CoCrMo alloy using the powder-pack boriding process at temperatures between 1223 and 1273K using various exposure times for each temperature. The mechanical characterization of the boride coatings was divided into two procedures: first, Vickers indentations were conducted at constant distances from the surface using loads ranging from 15 to 450mN. For the entire set of experimental conditions, the behavior of the indentation load as a function of the diagonal length (dm) was examined on the CoB and Co2B coatings. Second, the crack lengths emanated on the corners of the indentations marks (with applied loads above 250mN) were measured on both coatings using a scanning electron microscope (SEM).
Based on the indentation results, the KC values of the cobalt boride coatings were estimated using the universal crack equation, which is applicable independent of the cracking mode. The results indicated that the CoB and Co2B coatings exhibited two types of cracking modes (intermediate and radial-median, respectively), and that the fracture toughness of the Co2B coating was ten-fold greater than that of the CoB coating.
•New fracture data for cobalt boride coatings were estimated using indentation.•The presence of two cracking modes was observed on the CoB and Co2B coatings.•The fracture values of the coatings were obtained by the universal crack equation.
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