Hardness Of Specimens Research Articles

Cinnamaldehyde is a biologically active compound for the disinfection of removable denture: blinded randomized crossover clinical study

BackgroundFungal infections associated with the use of dentures, like denture stomatitis, are difficult to prevent and treat. This in situ study aimed to investigate the efficacy of cinnamaldehyde for the disinfection of complete removable dentures, and the effect on the physical and mechanical properties (Vickers microhardness, color, and surface roughness) of the acrylic resin.MethodsAcrylic resin disks were inserted into the dentures of a probabilistic sample of 33 complete denture users, that used cinnamaldehyde (27 μg/mL) and 0.5% sodium hypochlorite solutions in a 20 min/7-days protocol of dentures immersion in each solution, with a wash-out period of 7 days, to constitute a crossover-study. The disks were analyzed before and after the immersion, for the presence of microorganisms (CFU/mL) and by scanning electron microscope (SEM). Also, the surface roughness (Ra) and Vickers microhardness were measured, and color parameters were analyzed using the National Bureau of Standards (NBS) method. Data was analyzed by Wilcoxon and Friedman (microbiological evaluation), paired t-test (color and roughness) and independent t-test (Vickers hardness) (α = 0.05).ResultsA significant reduction (P < 0.05) in the number of microorganisms was observed for each species (total microorganisms, Streptococcus mutans, and Candida spp.), with no significant differences (P > 0.05) between hypochlorite and cinnamaldehyde. There was an increase in the roughness and a decrease in the hardness of the test specimens, with no difference between the two disinfectant substances (P > 0.05). Both hypochlorite and cinnamaldehyde also caused changes in color, considered as “perceptible” by the NBS classification, but with no significant difference between disinfectant substances (P < 0.05), and under the clinically acceptable limit (ΔE ≤ 3.7).ConclusionThe 27 μg/mL cinnamaldehyde solution was effective against all evaluated microorganisms and caused minor alterations in hardness, surface roughness, and color parameters, with no clinical relevance.

Investigation on microstructure and mechanical properties of HfB2-SiC-HfC ternary system with different HfC content prepared by spark plasma sintering

HfB2-based ultrafine composites with 25 vol% SiC and various volume fractions of HfC (5–20 vol%) have been successfully fabricated using spark plasma sintering. The composites were sintered in both 1800 °C and 1850 °C for different soaking times of 5 and 15 min and flexural strength, hardness and fracture toughness of specimens were measured. Sintering mechanism and mechanical properties of composites and HfC impact on them were investigated. The highest relative density (99.97 ± 0.02%) and the lowest apparent porosity (0.07 ± 0.03) were obtained for the specimen with 15 vol% of HfC. This composite also showed the maximum flexural strength (592 ± 17 MPa) and fracture toughness (4.98 ± 0.12 MPam1/2), even more than the composite with 20 vol% of HfC which had the highest Vickers hardness (22.7 ± 0.9 GPa).

Welded Stainless Steel: Surface Oxidation, Characterization, Hardness and Corrosion Resistance

This research presented the surface oxidation of stainless steel grade 304 (S304) welded by a gas tungsten arc welding (GTAW) process. The welded S304 was inspected by visual and penetrant testing methods. The surface of the welded specimen was oxidized by the chromic solution to an obtained oxide film on S304 welded specimen. After that, the structural phase and crystallite size of the oxide film were investigated by X-ray diffractometer (XRD). The thickness of the obtained film was analyzed by an atomic force microscope (AFM). Furthermore, the effects of the oxide film on hardness and corrosion properties of specimen were analyzed by Vickers hardness tester and potentiostat instrument to study the correlation between the property of oxide film and the surface properties of the welded pipe S304 after oxidation.

Effect of Different Curing on Mechanical Properties of Polymer - Cement Composites

The polymer-cement composites have special specifications, high strength compared to their low density, satisfactory deformability, deterioration resistance, tailored design. This enables the construction of new elements and the structural recovery of the existing parts made of traditional materials. two sets of mixtures were prepared that consist of mortar and polymer to produce the polymer-mortar composites were cured at room temperature and post-cure at 50 ͦ C. The set includes mortar (cement-sand) without water. The polymer was epoxy which is added to the mortar after mixing the hardener with resin. Set consists of the proportion of polymer (15, 20 and 30%).The effect of the polymer was studied on both sets by computing the density also measuring the hardness, compressive strength and flexural strength of specimens. The addition of polymer showed an improvement in these properties and post-cure have improvement properties .the lowest percent of the polymer showed The highest results were density 1133.3 kg/m3, the hardness of composites was 97.28 shore D. the compressive strength was about 100.816 MPa and the value of flexural strength was about 29.418 MPa.

Synthesis and characterization of sodium calcium fluorophosphate glasses containing MoO3 for potential use in sealing applications

A low-melting group of glass was prepared to examine the function of MoO3 on the synthesis and properties of sodium calcium fluorophosphate glasses. The glass specimens were synthesized based on Na2OCaOMoO3P2O5CaF2 system by the melting quenching method. The effect of adding MoO3 at the expense of CaO on the structure, mechanical, thermal, and chemical properties of the glasses was studied. The FTIR results proved that there is no evidence of a formation of the Mo-O linkages in the infrared spectral range. The density and molar volume of the prepared glasses were studied. Glass density enhanced whereas molar volume declined with MoO3 content. The Vickers hardness of the glass specimens was found to be decreasing with the MoO3/CaO replacement percent due to the weakening of the glass structure. The dilatometric thermal measurements showed the decrease of both transition temperature Tg and softening temperature Ts with MoO3 content. However, the thermal expansion coefficients values were increased from 101 × 10−7 to 110 × 10−7/°C1. The chemical solubility of the prepared glasses was examined by immersing in distilled water for 21 days. The results showed that the MoO3/CaO replacement helped to improve the glass solubility significantly. So, depending on the properties examined the glasses have the potential to be used as promising low-melting sealing materials.

The Study of Physical Properties and Analysis of Welding Parameters of A Butt Joint of C45 Steel in MIG Welding

This project shows the effect of welding variables on the mechanical properties of C45 steel. This medium carbon steel plate of 10 mm thickness welded using the Metal Inert Gas Welding. Welding current, voltage, root gap are the welding parameters. The hardness and tensile strength of weld specimen are investigated in this study. The results showed that the selected welding parameters had significant effects on the mechanical properties of the welded samples. The welded samples were cut and machined to standard configurations (dog bone sample) for tensile and hardness tests. The selected three input parameters were varied at three levels on the analogy; nine experiments were performed based on L9 array of Taguchi’s methodology, which consist three input parameters. Analysis of variance (ANOVA) was employed to find the levels of significance of input parameters. Root gap has greatest effect on tensile strength followed by welding current and voltage. Voltage has the greatest effect on hardness followed by root gap and welding current. The relative studies of machining performances on the basis of metallurgical properties are properties are prepared by the help of statistical tools, i.e. L9 Orthogonal Array, ANOVA etc.

Improving the applicability of wear-resistant Al–10Si–0.5 Mg alloy obtained through selective laser melting with T6 treatment in high-temperature, and high-wear environments

This study investigated the effects of T6 treatments on the microstructural evolution process and mechanical properties of Al–10Si–0.5 Mg alloy specimens fabricated through selective laser melting (SLM). The applicability of the wear-resistant alloy for high-temperature applications was evaluated. The results reveal that the volume energy density (VED) of the laser used influences the structural morphologies of the SLM-fabricated alloy components. Ultrafine crystals and residual stress formed in the SLM-fabricated alloy specimen due to the rapid cooling rate, thus causing high hardness, high strength, and extremely low elongation values. T6 heat treatment decreases the hardness and tensile strength values of the alloy specimens but improves their elongation values because the residual stress is releases and the microstructure is changes such that a large number of Si particles are present in the Al matrix. The mechanical properties are influenced by the Si particle distribution due to tensile crack initiation at hard–brittle Si particles. The mechanical properties of the as-fabricated SLM alloy are comparable to those of 4384 alloys obtained after T6 heat treatment. The SLM-fabricated specimen that presents a high VED value after T6 heat treatment exhibits good wear resistance. The as-fabricated SLM alloy specimen retained its mechanical properties according to high-temperature tensile tests. The SLM-fabricated Al alloy is a potential candidate for wear-resistance and high-temperature applications.

Density Functional Calculations of Elastic and Thermal Properties of Zinc-Blende Mercury–Cadmium-Chalcogenide Ternary Alloys

Density functional calculations are carried out on elastic and thermal properties of zinc-blende specimens within HgxCd1−xS, HgxCd1−xSe and HgxCd1−xTe ternary systems. Elastic stiffness constants decrease almost linearly with increasing Hg-concentration in each system. Each cubic sample is mechanically and dynamically stable, elastically anisotropic, compressible against elastic deformation, ductile and fairly plastic. The hardness of specimens in each system reduces almost linearly with enhancement in Hg-composition. Mixed kind of bonding with dominancy of ionic bonding over covalent, central nature of interatomic forces and bond bending over stretching exist in all specimens. In each system, covalency, Debye temperature and frequency, Debye temperature for acoustic phonon, thermal conductivity and melting temperature of specimens decreases, while Philip ionicity and Gruneisen parameter increases with increasing Hg-concentration.

Influence of secondary phase particles Al2O3/SiC on the microstructure and tribological characteristics of AA7075-based surface hybrid composites tailored using friction stir processing

Recently, cylinder liners of automotive and aircraft engines are encountered severe wear due to piston slap occurred by the repeated sliding stroke of piston. This research focuses on providing an alternative material for cylinder liners, which can be obtained through friction stir processing on AA7075 with different weight ratios of reinforcements like Al2O3 and SiC. Friction stir processing is executed with a tool rotational speed of 1000 r/min and traveling speed of 56 mm/min at 2° tool tilt angle. The images of optical microscopy reveal the fine-grains with a homogeneous distribution of secondary phase particles and also offer decrement in particle clustering except at some localized regions. It is identified that addition of 3.7 wt.% Al2O3 + 3.0 wt.% SiC in AA7075 enhanced the microhardness about 33.96% higher than base matrix. Hence, wear resistance of the specimen is improved. Dry sliding wear behavior of specimens is analyzed using pin on disc at 20, 40, and 60 N load conditions to create the actual sliding behavior of piston on cylinder wall. Increasing the wt.% of Al2O3 particles enhanced the wear resistance of AA7075 surface hybrid composites at 20 N load due to the formation of protective tribofilm. Specimen with 3.7% Al2O3 + 3.0% SiC has better lubrication and load-bearing capacity that exhibits superior tribological behavior at 40 and 60 N. Higher Fe content of 5.44 wt.% has been obtained through spectroscopy analysis in S5, which is 8% and 6% higher than S3 (7.5% of Al2O3) and S7 (6% of SiC), respectively. The scratching action of this hard specimen on the counterpart brings more Fe content. Increase of Al2O3 particles paved the way for tribofilm formation and identified through scanning electron microscopy micrographs. The observation from worn specimens shows that finer wear debris had increased by adding more quantity of SiC particles due to abrasive wear mechanism.

OPTIMIZATION OF MECHANICAL PROPERTIES OF WIRE ARC ADDITIVE MANUFACTURED SPECIMENS USING GREY-BASED TAGUCHI METHOD

In present work, the optimization of mechanical properties of specimens accumulated by Wire Arc Additive Manufacturing (WAAM) process is done using Grey-based Taguchi method. ER4043 MIG wire of 1.2mm diameter specimen material and 6061 aluminumas substrate are selected for analysis. Initially, the specimens are fabricated by using Cold Metal Transfer (CMT) welding machine with a linear manipulatorby changing process parameters like Gas pressure, Current, Nozzle to tip distanceby following L9 Orthogonal Array (OA). Mechanical tests are conducted on specimens like, Micro tensile test and Micro Hardness test. From the output responses (test data)Grey-based Taguchi analyses and Grey based ANOVA test is performed.Finally, Maximization of Ultimate tensile strength (UTS) and Hardness of the WAAM specimens by Grey based Taguchi analysis and identified the percentage of contribution of each process parameters by using Grey based ANOVA.

Investigation of the Surface Properties and Wear Properties of AISI H11 Steel Treated by Auxiliary Heating Plasma Nitriding

This paper presents an auxiliary heating method to maintain a uniform specimen temperature and precisely control nitriding temperature during plasma nitriding. The surface properties and wear properties of AISI H11 steel treated by auxiliary heating plasma nitriding are investigated. Firstly, the specimens with different diffusion layers and different hardness levels are fabricated through changing the plasma nitriding temperature. Secondly, the surface properties of the plasma-nitrided H11 steel specimens are characterized by a scanning electron microscope (SEM), X-ray diffractometer, metallographic microscope and microhardness tester. The results show that the surface hardness of the plasma-nitrided specimen is almost twice as high as that of the untreated specimen. The thickness of diffusion layer increases with the increase of nitriding temperature. However, the surface hardness firstly increases and then decreases with the increase of the nitriding temperature. Finally, the wear properties of untreated and plasma-nitrided H11 steel specimens are investigated under different friction conditions. The results show that the plasma-nitriding method can significantly improve the wear resistance of AISI H11 steel. The friction coefficient fluctuations of the plasma-nitrided specimens are all lower than those of the untreated specimens. In addition, the wear rates of the plasma-nitrided specimens rise along with load, and reduce along with the sliding speed and friction temperature.

Study of the Effect of a Corrosive Medium on Medium-Carbon Steel Surface Layer Microhardness Subjected to Impact Electromechanical Treatment

The influence of a corrosive medium on the transformation of strength properties of a steel 45 surface layer subjected to impact electromechanical treatment is studied. Results are provided for a study of the effect of impact electromechanical treatment regimes on the corrosion activity of strengthened specimens, estimated by the change in hardened surface layer microhardness. The nature and degree of reduction in strengthened surface layer hardness in specimens strengthened with current density j = 100, 300, and 600 A/mm2 are established in relation to corrosion test duration.

Ageing condition of tensile specimens: fracture behavior of notched Al2024 sheet under tensile loading

The effect of different (T6 and T8) heat treatments on tensile properties and fracture behavior of Al2024 in presence and absence of notch by means of microhardness, tensile tests and scanning electron microscopy were investigated. Tensile and hardness specimens were subjected to two different artificial ageing (T6 and T8 heat treatment) for various times. These included under ageing (UA), peak ageing (PA) and over ageing (OA). T8 heat treatment, which has a cold rolling between solutionizing and ageing in its steps, showed a higher value of hardness and yield strength in comparison with common artificial ageing of T6 heat treatment. In notched-tensile specimens, yield stress was found to increase up to the peak ageing condition with a simultaneously decrease in elongation at fracture. This behavior was converse at OA condition. Although introducing of notch increase the yield stress of samples under T6 and T8 conditions in comparison with un-notched samples, the notch strengthening phenomenon was observed only under T8 treatment. Despite of an enhancement in strengthening by applying notch on tensile samples, the elongation to failure was notably lessen in both notched-heat treated samples in comparison with un-notches ones. Also, it was confirmed that the toughness of notched samples of both heat treatments at PA condition were significantly lower than un-notched ones. Consequently, toughness decrement was considerably dominated by the role of deformability compared to strengthening factor, however, the presence of cold rolling in the process of heat treatment (T8) could reduce the harmful effects of notch by increasing the stress bearing capacity in contrary with T6 heat treatment. Moreover, inserting the mechanical properties of peak aged samples from the un-notched tensile test in Abaqus finite element software; the V-shaped notch tensile test was simulated and confirmed the experimental results. It was shown in SEM results that the presence of notch enhanced the contribution of cracked particles, compared to particle/matrix deboning and matrix deformation, therefore, the non-homogeneous distribution of fracture features confirmed the harmful effect of notch. In the following, the distribution of three fracture micro-mechanisms were homogeneous in un-notched samples, which demonstrated the superior values of toughness in smooth samples. The present finding sheds light on development of processing techniques to optimize the mechanical properties of Al 2024 alloy.

Effect of plant-extract disinfectant solutions on the specific properties of reinforced maxillofacial silicone elastomers with nanofiller and intrinsic pigment

Abstract Objective This study aimed to evaluate the effects of disinfectant solutions, namely, the alcoholic extract of Salvadora persica L. (A1 = 10% and A2 = 15%) and chlorhexidine digluconate (A3 = 2%), on the tear strength and hardness of room temperature vulcanizing (RTV) VST50F and heat temperature vulcanizing (HTV) Cosmesil M511 silicone elastomers before and after reinforcement with nanofillers (TiO2) and intrinsic pigment. Materials and Methods: A total of 320 specimens were prepared, with 160 specimens each for RTV and HTV silicone. Forty specimens were evaluated before disinfection and divided into two equal groups, namely, control (without additive) and experimental (with additive) groups, for tear strength and hardness tests. The 120 specimens were divided into three equal groups, with two equal subdivisions for tear strength and hardness tests, and were evaluated after disinfection. ANOVA and Tukey's honest significant difference tests were conducted for group comparisons (significance level set at P &lt; 0.05). Results: The tear strength of all groups decreased after disinfection, with the highest values in the experimental group. Most comparisons showed significant differences. A1 exhibited no significant effect on the tear strength and hardness of the HTV control and the hardness of the RTV experimental specimen. The hardness of the HTV control was not significantly affected by A3. A1 with A3 did not significantly affect the tear strength and hardness of the RTV control and the tear strength of the RTV experimental specimen. The results of comparisons between A1 and A2, and A1 and A3 in the HTV tear strength of the experimental group and the A2 and A3 of the control and experimental groups were not significant. Conclusions: S. persica L. can be used as a natural disinfectant agent. The reinforcement of maxillofacial silicone prosthesis can extend its survival duration.

A study on effect of chill casting on A356 reinforced with Hematite metal matrix composite

The Present scenario in industries has huge demand in high strength and lightweight materials of aluminum alloy and its composites. In this paper an attempt is made to study the influence of copper chills in Aluminum alloy metal matrix composites. A356-Hematite particulate composites were fabricated through stir casting technique followed by sand moulds with and without copper chills, by varying weight percentage of Hematite particulates from 0 wt%, to 12 wt% in steps of 3 wt%. The test samples were prepared according to ASTM standards. The prepared samples have undergone microstructure, hardness, tensile and compression tests. The microstructure revealed that uniform distribution of Hematite particulates in the A356 matrix alloy and the rapid cooling rate helped to get fine grained structure. The use of copper chill in turn improved the hardness, tensile strength, and compressive strength of the chilled composite specimen as compared to as-cast specimen.

Investigation on the Case-Hardening Behavior of Additively Manufactured 16MnCr5

Additive manufacturing (AM) technologies, such as laser-based powder bed fusion of metals (PBF-LB/M), allow for the fabrication of complex parts due to their high freedom of design. PBF-LB/M is already used in several different industrial application fields, especially the automotive and aerospace industries. Nevertheless, the amount of materials being processed using AM technologies is relatively small compared to conventional manufacturing. Due to this, an extension of the material portfolio is necessary for fulfilling the demands of these industries. In this work, the AM of case-hardening steel 16MnCr5 using PBF-LB/M is investigated. In this context, the influences of different processing strategies on the final hardness of the material are studied. This includes, e.g., stress relief heat treatment and microstructure modification to increase the resulting grain size, thus ideally simplifying the carbon diffusion during case hardening. Furthermore, different heat treatment strategies (stress relief heat treatment and grain coarsening annealing) were applied to the as-built samples for modifying the microstructure and the effect on the final hardness of case-hardened specimens. The additively manufactured specimens are compared to conventionally fabricated samples after case hardening. Thus, an increase in both case-hardening depth and maximum hardness is observed for additively manufactured specimens, leading to superior mechanical properties.

Evaluación de la capacidad de absorción de energía de impacto y dureza en probetas impresas en 3D de PLA y ABS con estructura cúbica y tri hexagonal

En la actualidad se construyen ortesis personalizadas para rehabilitación física mediante prototipado rápido 3D, debido a esto es de importancia conocer su resistencia mecánica, por esto se plantea ensayar probetas impresas en 3D con filamentos de PLA y ABS. Las probetas de estudio se diseñaron mediante software CAD, en función de la norma ASTM D256; después se imprimieron en 3D con estructura de relleno cúbica y tri hexagonal en materiales de PLA y ABS. Para el análisis de resistencia de las probetas se desarrolló varios ensayos: el ensayo de impacto con péndulo tipo Izod, microscopia de la superficie de rotura y el análisis de dureza SHORE D. En función de los resultados obtenidos se determinó que la probeta impresa en 3D con ABS ofrece mayor absorción de energía de impacto con respecto a la probeta de PLA; la estructura de relleno de la probeta que da mayor resistencia mecánica es la estructura cubica comparado con la estructura tri hexagonal. Además se determina que la dureza de la probeta de PLA es mayor que la probeta de ABS, finalmente se observó que la fractura de la probeta de PLA es lineal, mientras que la fractura de la probeta de ABS es tiene una forma de zigzag.

Effect of nano-vanadium nitride on microstructure and properties of sintered Fe-Cu-based diamond composites

With FeCu30 pre-alloy powder as the main component of the bond, a new type of nano‑vanadium nitride (VN) additive with different concentrations was introduced into Fe-Cu-based diamond composites to investigate the effect of nano-VN on the microstructure and properties of Fe-Cu-based diamond composites. The hardness, relative density, bending strength and wear loss weight of the fabricated specimens were tested, and then the fracture surfaces and worn surfaces of those specimens were analyzed using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results show that the Fe-Cu-based diamond composites with nano-VN addition exhibited an improvement in the mechanical properties, plasticity and wear resistance, which can be attributed to the dispersion strengthening and grain refinement caused by nano-VN. And the nano-VN can also activate sintering, which can significantly improve the wettability of the binder to diamonds, resulting in more binder elements wetting and diffusion on the diamond surface during the sintering process. Besides, the diamond composites showed the best properties with the addition of 2% nano-VN. That is, the bending strength and the HRB hardness of the diamond composites increased by 25% and 20%, respectively, and the wear resistance of the matrix and holding force coefficient of the matrix to diamond were improved significantly. But an excessive amount of nano-VN was detrimental to the mechanical properties of Fe-Cu-based diamond composites.

Effect of build orientation on the manufacturing process and the properties of stereolithographic dental ceramics for crown frameworks

Statement of problemStereolithography (SLA) ceramic crown frameworks are suitable for clinical use, but the impact of SLA build orientation has not been identified. PurposeThe purpose of this in vitro study was to investigate the effect of 3 build orientations on the physical and mechanical properties and the microstructure of SLA alumina dental ceramics. Material and methodsThe physical and mechanical properties and microstructures of 3 different oriented SLA alumina ceramics (ZX, ZY, and XY) were evaluated by visual observation, hydrostatic weighing (n=10/group), Weibull analyses (n=30/group), scanning electron microscopy, 3-point flexural strength (n=30/group), fracture toughness (indentation, single-edge-V-notched-beam) (n=4/group), and Vickers hardness (n=15/group) testing. The hydrostatic weighing, 3-point flexural strength, fracture toughness, and Vickers hardness testing data were statistically analyzed (α=.05). ResultsThe minimum resting period of slurries between the polymerization of 2 layers was shorter for the ZY- and ZX-oriented specimens and increased with the layer surface. The density and Vickers hardness of the SLA-manufactured specimens were similar for all groups (P>.05). The 95% confidence intervals of the Weibull moduli of the ZX- and ZY-oriented specimens were higher than that of the XY-oriented specimens, with no overlap fraction. The ZY-oriented specimens displayed significantly higher 3-point flexural strength (P<.05) and fracture toughness as evaluated by the single-edge-V-notched-beam method than the ZX-oriented specimens (P<.05). They also displayed significantly higher 3-point flexural strength than the XY-oriented specimens (P<.05). The microstructural analysis showed that the texturing was heterogeneous and that the major axis of the large grains of alumina ran parallel to the orientation of the layers. ConclusionsThe ZY orientation produced a reliable dental ceramic by SLA, with the shortest general manufacturing time and the highest mechanical strength when the layers were perpendicular to the test load surface.

Effect of cooling rate on hardness and microstructure of Pd–Ag–In–Sn−Ga alloy during porcelain firing simulation

This study examined the effect of the cooling rate on the hardness and its effect on the microstructure during porcelain firing simulation of a Pd–Ag–In–Sn−Ga metal-ceramic alloy. In practice, after each firing step for porcelain bonding, the prosthesis is cooled to room temperature before proceeding to the next firing step. The cooling step is known to allow the hardness of the metal substructure to increase. The aim of the study was to determine whether controlling the cooling rate after each porcelain-firing step increases the hardness of the Pd–Ag-based metal-ceramic alloy. The results showed that the hardness of specimens cooled at a higher cooling rate increased after each firing step compared to specimens cooled at a lower cooling rate (p < 0.05). During cooling after the firing simulation the InPd3–based phase of tetragonal structure precipitated from the Pd–Ag-rich matrix of the face-centered cubic structure. Hardening by cooling at a higher cooling rate after firing was the result of the coherency strains that formed at the interface of the Pd–Ag-rich matrix and the metastable phase based on the InPd3 phase. . The reduced hardness obtained in the specimen cooled at a lower cooling rate after firing resulted from the loss of coherency strains as the fine metastable phases based on the InPd3 phase were transformed into the coarser stable phase with decreased (c/a) of 0.88. This finding revealed that controlling the cooling rate during porcelain firing simulation improves the hardness of the Pd–Ag–In–Sn−Ga metal-ceramic alloy without an additional heat treatment of the alloy.