This paper presents a Novel method for fabricating of thin ceramic plates. Although achieving nearly full density, the commercial hot pressing machine have extremely high price and upkeep cost. The device presented in this paper have lower cost and for hot pressing, needs just an ordinary electrical furnace.Despite all this benefits, it can just form thin ceramic plates. In this paper, initially a brief description about ceramic matrix composites (CMCs) is presented and the effect of formed components and forming methods on its properties is discussed. Then the powder forming methods with advantages and disadvantages is presented. In the next step the device (expansional hot pressing device) and its working method is introduced. And finally this device is used for forming of a special ceramic matrix composite and the mechanical and microscopic properties of the formed part is examined and the method proves to be useful for forming CMCs.

In the present study, the microstructural changes of a Nickel based superalloy Nimonic 80A during a non-isothermal deformation were studied. Therefore, microstructure evolution during hot side pressing test was predicted with combined methods of finite element analysis and processing map of the material. The predicted results were validated through experimental microstructural studies. The results show that the distribution of deformation parameters (i.e. strain, strain rate, and temperature) is non-uniform in the deformed samples. The severity of this non-uniformity depends on the amount of sample reduction. High reduction value at one step forging can cause flow localization and non-uniform dynamic recrystallization, which results the formation of adiabatic shear bands, while using the lower reduction value at each forging step, leads to more uniformly distribution of the deformation parameters and thus uniform the dynamic recrystallization with the stable flow. Hence the workability and microstructure of the Nimonic 80A alloy are mainly depends on the deformation path.

The objective of the present work was to study the preparation a fully dense MgO+C dopped alumina. The sintered materials was characterized by their microstructure and the microstructure variation during the different thermal treatment. The atmosphere is suggested to play an important role during the annealing of MgO+C dopped Al2O3. From the results it can be seen that MgO+C increased the densification rate of Al2O3 and the density is arrived very near the theoritical density. The Vaccum secondary and the absence eventually gas in the pores have been played in the densification rate. The other role of MgO+C in powder is to lower the boundary mobility which helps to keep the pores attached to the moving boundary even though the pores are controlling grain growth and not to change the grain size/density significantly. That is to say, the pesence of carbon or MgO in powder is to inhibit grain growth and to promote the development of more uniform grain structure by formation the precipitate and segregation. Because of the above roles of MgO+C in Al2O3, it is possible to arrive the theoritical density without the abnormal grain.

Aluminum matrix composites have recently gained increased attention for structural applications in many industries due to their excellent properties. In this research, machining scraps of coarse-grained Al2024-T3 alloy were used to prepare nanostructured Al2024 alloy and Al2024-2wt. %TiO2 nanocomposite. Then, tribological behavior of bulk nanostructured Al2024 alloy and Al2024-2wt. %TiO2 nanocomposite, produced by 10 h of mechanical alloying and subsequent hot-pressing at 500  C for 20 min, was investigated. Hardness measurements on the samples revealed that the hardness value of mechanically alloyed and hot-pressed Al2024 alloy reached a value of  198 HV, which was  41% higher than that for the initial coarse-grained Al2024-T3 alloy (140 HV). The average hardness values of Al2024-2wt. %TiO2 nanocomposite was found to be 238 HV, which showed ~ 20% increase compared with that for the nanostructured Al2024 alloy. The wear resistance of samples changed in the order of coarse-grained Al2024 alloy

In this research, the effect of the hot-pressing process on the microstructure and hardness of A390 cast aluminum-silicon alloy was investigated. The results were prepared using an optical microscope and hardness tester. The microstructure of the casting sample included very coarse primary silicones, acicular eutectic silicones, intermetallic compounds, and large alpha-phase dendrites. By increasing the amount of strain in the hot-pressing process, primary and eutectic silicones as well as intermetallic compounds were broken and finer, and their distribution in the alpha matrix became more uniform. The obtained results showed that the microstructure of the casting alloy has been improved in terms of the modification of primary silicon particles, eutectic silicon, and intermetallic compounds, as well as the uniform distribution of these particles and the removal of porosity. The initial silicon size is dramatically reduced from over 100 µm (for the cast sample) to less than 5 µm (after the seventh pass). By increasing the strain up to the fourth pass, the hardness of the alloy decreased from 87 to 65 HB. With the further increase of the strain from the fourth pass to the seventh (final) pass, the hardness value increased to 81 HB.

In the current study, nanocrystalline Finemet soft magnetic cores were processed and their thickness was improved by the hot pressing technique. Besides, the effect of hot pressing on the microstructure and soft magnetic properties of the amorphous precursor was compared with the conventional annealing method. First, amorphous Finemet ribbons were produced through the melt-spinning method. Thermal behavior of the amorphous Finemet ribbons and crystallization of the anocrystalline phase was studied by Differential Scanning Calorimetry. Thus, the proper crystallization temperature of the amorphous phase was specified about 550oC. To crystallize the nanocrystallime phase from the amorphous matrix, the produced ribbons were either annealed conventionally at 550oC for 30 min or hot pressed at the same temperature for 60 min, under a controlled H2/Ar atmosphere, a 30% H2, 70% Ar mixture. The formed phases were specified by X-ray diffraction, and microstructure of the formed alloy was evaluated by scanning electron microscopy. It was shown that, both methods result in the formation of a-FeSi nanocrystals embedded in an amorphous matrix. The average size of the formed a-FeSi nanocrystals was calculated by using the MAUD software, came out to be 17 and 12 nm, for annealed and hot pressed samples, respectively. Hence, hot pressing results in crystal size reduction, compared with the conventional annealing method. Moreover, this processing method can decrease the soft magnetic properties of the amorphous precursor. However, the produced cores exhibit good soft magnetic properties (Hc~ 8 Oe, δ~130 emu/g).

The aim of current research was to examine the microstructure and mechanical properties of Aluminium matrix hybrid nano-composite reinforced with carbon nanotube (CNT) and silicon carbide whisker (SiCW) prepared by hot pressing. Hybrid nano-composites were fabricated with different amount of CNT and SiCW (0-5 weight percent) in equal proportion. In order to distribute the reinforcements، Al powder and the reinforcements were mixed in a planetary ball mill with a speed of 120 rpm for one hour، and then compressed samples were produced under the pressure of 500 MPa at 550oC for 45 minutes. Followed by composite fabrication، Vickers microhardness and compressive strength test were performed and microstructural observations were undertaken using field emission scanning electron microscopy (FESEM). The results showed that by increasing the amount of reinforcements up to 1 percent، mechanical properties of nano-composites increase; while، by increasing the amount of reinforcements from 1 to 5 percent، mechanical properties of nano-composites decrease due to the agglomeration of CNTs and non-uniform dispersion of SiCW.

MAX phases are an attractive class of layered solids that have recently attracted a great deal of attention due to their unusual and unique composition. The ternary compound Ti3SiC2 is an example of a material that combines the properties of ceramics and metals. As a ceramic, they are high stiff. Some of them are resistant to oxidation, creep, fatigue, corrosion. They are extremely refractory and have a high melting temperature. Also, their strength remains stable with temperature. When considered as a metal, this compound is a conductor of electricity and thermal and is not prone to thermal shock, has easy machining with a variety of modern tools, is relatively soft and also has high chemical resistance. Combining SiC with Ti3SiC2 for fabrication the composite is an effective way to improve the high temperature properties, because SiC as a reinforcing phase has good oxidation resistance, high hardness, abrasion resistance, and in addition, it is compatible with Ti3SiC2 at high temperatures. Fully-dense Ti3SiC2 –SiC composites were in-situ synthesized and sintered through a reactive hot-pressing process using TiC and Si powders with different molar ratios of 3TiC:3Si, 3TiC:2Si (stoichiometric composition), and 3TiC:1.5Si. Phase characterization of the hot-pressed specimens was performed by X-ray diffraction (XRD) analysis, and the microstructures were studied by scanning electron microscope (SEM). The mechanical properties of the hot-pressed composites were investigated in terms of Vickers hardness, fracture toughness, and flexural strength. It was found that the in-situ synthesized SiC particles, with platelet morphology, have been distributed in the in-situ formed Ti3SiC2 matrix. The highest Vickers hardness belonged to the 3TiC:1.5Si sample with a value of 14.2 GPa, related to the presence of SiC and residual TiC phase in the microstructure. The flexural strength enhanced with increasing the molar value of Si, due to the presence of the free Si phase in the sample and the further formation of the SiC phase. The 3TiC:3Si sample achieved the highest fracture toughness of 10.1 MPa.m1/2 and the highest flexural strength of 576 MPa.

Hot isostatic pressing (HIP) is a manufacturing process used in powder metallurgy science. It can be used to consolidate a powder, enhance the properties of a single crystal, solidify a cast blade in a specified direction and generally, densify a cold pressed, sintered or a cast part. The numerical simulation of the thermofluidic responses of working gases can provide important and detailed information about the dynamics of fluid flow and heat transfer in a HIP furnace. This information cannot be obtained from experimental observations. The experimental investigation of such a high temperature and pressure process is quite expensive. Moreover, the high working pressure and temperature limits the application of probes and sensors that may enable detailed data collection. This paper presents the modeling procedure and the results of a numerical investigation of a HIP furnace. The effects of the heater temperature, the performance of the cooling water system, and the presence of a radiation shield in front of the element were studied for two working gases. Moreover, investigation of the element heat flux and the temperature variation of the furnace could be used to choose a proper element and design an accurate control system. In order to increase the accuracy of the results, a real gas thermodynamic model has been also employed. In terms of physical modeling, the momentum and continuity equations and a two-equation turbulence model were coupled with the energy equation and radiation correlations. The results indicate that the final furnace pressure is directly influenced by the performance of the cooling system and the initial furnace pressure. A linear relation between the final and initial furnace pressure is observed. In addition, the final pressure is dependent on the type of the working gas whereas the temperature distribution is not significantly varied by gas selection. Based on the results, existence of the radiation shield causes non-uniformity in the flow field and temperature distribution of the hot zone area. The thermal conductivity of the furnace wall has a significant effect on the furnace heat loss. As the thermal conductivity increases tenfold, heat loss increases by 700 percent.