Thermodynamic Study of Adsorption Capacity between Metal Film and Optical Crystal: Adsorption Energy of Ni Films on LiNbO3 Substrates

The growth of large areas of two-dimensional homogeneous graphene depends on the bond between the metal film, which acts as a catalyst, and the substrate material. The structural differences between the metal and the various anisotropic crystals make this growth method a challenge for the feasibility of growing graphene on optical crystals. In this paper, the evolution of the adsorption energy between nickel (Ni) films and Lithium Niobate (LiNbO3, LN) crystals is modelled under different thermal treatment environments by constructing a physical model of the temperature dependence of the adsorption energy between the two materials. With the aid of a series of simulated full annealing processes, the changes in adsorption energy at different temperatures were calculated. The results show that there are two “temperature windows” with target annealing temperatures of 700–800 K and 950–1050 K that prove to have high adsorption energies. This is of great guiding and practical significance for the direct transfer-free synthesis of graphene on LiNbO3 substrates.

Full-annealing and its effect on the Mechanical Properties of Alloy 304H Stainless Steel

Stainless steel is an alloy of steel which contains at least 10.5% chromium, less than 1.2% carbon, and other alloying elements and it is widely used in many industries globally and their properties are highly influenced by their microstructure, heat treatment or by plastic deformation. But due to hardness, poor wear, and corrosion resistance, leading to short service life, there is need to investigate the effect of annealing on the mechanical properties of alloy 304H stainless steel and how the mechanical properties can be improved with a view of improving its service life and optimizing engineering usage. Sixteen (16) samples of the alloy were used. Twelve (12) samples were annealed at three different temperatures of 950oC, 1000oC and 1050oC inside a muffle furnace. At each temperature four samples were heat-treated inside the muffle furnace for 30 minutes. The result showed that the yield strength decreased from un-annealed sample to annealed samples at 950oC with a value of 504.8MPa and increased at 1000oC with a value of 610MPa and a decrease of 323.8 MPa was obtained at 1050oC. Also, the ultimate tensile strength showed an increase from 950oC with a value of 826.3MPa to 1000oC with a value of 930MPa but there was a slight decrease at 1050oC for all samples. The ultimate tensile strength at 1000oC with a value of 930MPa was the highest in all the samples. The annealed samples at 1000oC had the highest percentage elongation of 13.57% which shows an increase in the ductility of the material. The hardness of the material decreased from 157.25 BHN at 950oC to 134.00BHN at 1000oC. An increase to 169.50BHN was however obtained at 1050oC. Thus, full-annealing of alloy 304H stainless steel at 1000oC increases in ductility as hardness decreases.

Effect of Alloying Additives and Microadditives on Hardenability Increase Caused by Action of Boron

The presented work was aimed at evaluating influence of boron on hardenability of steel quantitatively and evaluating this effect during complex use of boron with other alloying additives like chromium, vanadium and titanium. For this purpose, eight melts with variable chemical compositions were prepared. From the ingots, cylindrical specimens with normalized dimensions according to EN ISO 642:1999 were cut out and subjected to full annealing at 1200 °C and to normalizing at 900 °C. Such specimens were subjected to the hardenability Jominy test. In order to distinguish the influence of boron on hardenability of a given melt and thus to eliminate the differences resulting from its chemical composition, grain size and austenitizing temperature, the obtained ideal critical diameter was corrected and the boron effectiveness factor was determined. The performed examinations and analyses showed that inadequate quantities of microadditives result in losing the benefits coming from introduction of boron as the hardenability-improving element and can even result in a reduction of hardenability of the boron-containing steel.

Increased stability die forged steel 4H4N5M4

The results of researches on steel 4H4N5M4F2 modes thermo-deformation processing optimization are given. It is established that incomplete annealing (750 °С ± 20 °С in comparison with full annealing 860 °С) in cast and forged condition promotes to improve the machining of blanks for the manufacture of matrices. It is shown that the use of incomplete annealing, namely partial recrystallization promotes the formation of spheroidized rather than lamellar carbide phase, which leads to a decrease in the characteristics: strength threshold, yield strength, hardness 900 MPa, 800 MPa, 32 33 HRC in the cast state and 1200 MPa, 1050 MPa, 38 39 HRC in forged condition, respectively. This increases the fracture toughness: 180 J/cm2 in the cast state and 130 J/cm2 in the forged state. The optimized mode of forging at the temperature of 1170 ± 20 °С and heat treatment (hardening at 1100 ± 5 °С and tempering at 595 ± 5 °С) of steel 4H4N5M4F2 allowed to increase impact strength five times in comparison with cast experimental steel, and also to increase strength threshold of 100 MPa. Forged steel 4H4N5M4F2 has slightly lower heat resistance compared to cast, which hardens at temperatures above 630 °C during operation of the die steel tool. After operation of the extruder wheels made of investigated forged steel and forged steel 4H5MF1S, which was used at the enterprise in copper processing, the properties of both steels were determined. The investigated forged steel 4H4N5M4F2 is characterized by an increase in the strength threshold by 200 MPa and hardness by 6 HRC. After operation (production of 60 tons of copper products of M1 grade) the tool (wheel extruder) from H13 steel (analog 4H5MF1S) had micro and macrocracks on the side and inner parts, and in the investigated steel 4H4N5M4F2 such defects were absent. Thus, the studied steel is characterized by increased stability. Keywords: steel, heat treatment, forging, structure, physical and mechanical properties.

Karekteristik Proses Full Annealing Dengan Variasi Media Quench Terhadap Kekuatan Mekanik Aisi 1045

Baja AISI 1045 biasanya dipakai sebagai komponen automotif yang aplikasinya sering mengalami pembebanan, gesekan dan tekanan. Tujuan penelitian untuk pelunakan sehingga kekuatan Tarik, kekuatan Impak dan kekerasan menjadi lebih baik sehingga dilakukan proses full annealing quench oli dan air. Rata-rata kecepatan pendinginan adalah faktor menentukan kekerasan suatu material. Proses full annealing quench oli adanya pelunakan cukup baik yang menurunkan kekerasan dengan kekerasan tertinggi 3,5 HRC temperatur 8500C sedangkan quench air kekerasan tertinggi 43 HRC temperatur 8000C. Kekuatan impak quench oli tertinggi temperatur 7500C bernilai 10,95x104 Joule/m2 sedangkan quench air tertinggi temperatur 7500C bernilai 16,71x104 Joule/m2. Kekuatan ulur tertinggi pada suhu 8000C quench oli bernilai 949,02 N/mm2 sedangkan kekuatan ulur tertinggi pada suhu 7500C quench air bernilai 1683,23 N/mm2 tetapi material ini rapuh dibandingkan dengan quench oli yang mempunyai keliatan yang cukup baik.

INVESTIGASI KEKERASAN MATERIAL AISI 1045 PENGARUH PROSES FULL ANNEALING MENGGUNAKAN FULL FACTORIAL DESIGN

Pendinginan merupakan faktor yang menentukan kekerasansuatu material. Ada dua media quench yang sering dgunakan yaitumedia oli dan air. Quench oli adalah pendinginan yang lebih perlahansehingga mencegah retak akibat kecepatan akspansi materialdibandingkan dengan quench air. Pemaparan fenomena yang terjadidi lapangan untuk penggunaan elemen mesin yang terbuat dari bajakarbon sedang AISI 1045 dibatasi pada kegagalan elemen mesin yangdiakibatkan oleh beban personal atau beban mekanik. Metode FullFactorial Design of Experiment digunakan untuk mengkaji hasil ujikekerasan sesuai dengan hipotesa pengujian. Design of Experiment(DOE) telah banyak digunakan untuk menentukan faktor desain yangsignifikan mempengaruhi respons target dan membangun empirismodel yang mewakili hubungan antara faktor signifikan.Untuk mendapatkan respon kekerasan terhadap perlakuan panasfull annealing dengan media Quenching Oil dan air sehingga padapenelitian ini digunakan material AISI 1045 dengan variasitemperatur 7500 C, 8000 C dan 8500 C. AISI 1045 hasil produksikomersial dengan memotong sebagian kemudian diambil untukdilakukan pengujian kekerasan Metode Full Factorial Design ofExperiment digunakan untuk mengkaji hasil uji kekerasan sesuaidengan hipotesa sesuai analisis varians (Anova).Respon input data full factorial design pengujian kekerasandipengaruhi media pendingin dan temperatur proses full annealingpada material AISI 1045. Pengaruh media pendingin menghaslkanFo,5%, 2,18= 3,55,maka Fo=26,73>3,55 menunjukan pengaruh mediapendingin berpengaruh terhadap kekerasan AISI 1045 sedangkanpengaruh temperatur menghaslkan Fo, 5%, 2,18 = 3,55, maka Fo = 31,74> 3,55 menunjukan pengaruh temperatur berpengaruh terhadapkekerasan AISI 1045. Pengaruh interaksi media pendingin terhadaptemperatur menghaslkan Fo, 5%, 1,18 = 3,55, maka Fo = 6,58 > 4,41menunjukan pengaruh media pendingin berinteraksi temperaturberpengaruh terhadap kekerasan.

The influence of different heat treatment cycles on the properties of the steels HARDOX® 500 and STRENX® 700

The HARDOX® 500 and STRENX® 700 steels are quenched materials from hot rolling process. The HARDOX® 500 is a low alloy steel with high values of microhardness and mechanical strength, the STRENX® 700 steel is a low alloy steel structural used in applications, where low density is associated with high mechanical strength. In this work, the two steels were submitted to different heat treatments: quenched and tempering, normalization and full annealing. The effects of these heat cycles were analyzed by optical microscopy and Vickers microhardness techniques. It was concluded that in the normalization treatment, the microhardness reduction of HARDOX® was more significant than that one of STRENX®. In the quenched and tempering process, both presented higher microhardness compared to the originally produced and characterized material with higher austenitic grain refining. The HARDOX® presented an effective increase of microhardness. In the heat treatment of full annealing, the HARDOX® 500 and the STRENX® 700 steels had similar microhardness and microstructural morphology values.

Analysis the Effect of Temperature and Holding Time of Full - Annealing Heat Treatment to Micro Structure, Mechanical Properties, and Electrical Conductivity of Aluminium Copper (Al-Cu) Alloy

Good electrical conductivity properties of aluminium are the main reason this metal become an option as material of electrical devices. To improve the ductility and electrical conductivity properties, aluminium is combined with copper. The aim of this study is to analyze the effect of temperature and holding time of full-annealing heat treatment to the micro structure, hardness, and electrical conductivity of aluminium copper alloy (Al-Cu). In this research, pure aluminium with the addition of 4% copper (Cu) composition has been casted with gravity die casting mold made from ductile cast iron, and continued full-annealing heat treatment with 3 variations at temperature (2600C, 3500C, and 4400C), and 3 variations of holding time (2 hours, 3 hours, and 4 hours). It was found that the effect of higher temperature at the same holding time with the full-annealing heat treatment caused the grains of phase α become more regular and greater so that the hardness decreased and the electrical conductivity was increased.

Fabrication of Cu-W Nanocomposites by Integration of Self-Propagating High-Temperature Synthesis and Hot Explosive Consolidation Technologies

Manufacturing W-Cu composite nanopowders was performed via joint reduction of CuO and WO3 oxides with various ratios (W:Cu = 2:1, 1:1, 1:3, 1:13.5) using combined Mg–C reducer. Combustion synthesis was used to synthesize homogeneous composite powders of W-Cu and hot explosive consolidation (HEC) technique was utilized to fabricate dense compacts from ultrafine structured W-Cu powders. Compact samples obtained from nanometer sized SHS powders demonstrated weak relation between the susceptibility and the applied magnetic field in comparison with the W and Cu containing micrometer grain size of metals. The density, microstructural uniformity and mechanical properties of SHS&HEC prepared samples were also evaluated. Internal friction (Q-1) and Young modulus (E) of fabricated composites studied for all samples indicated that the temperature 1000 °С is optimal for full annealing of microscopic defects of structure and internal stresses. Improved characteristics for Young modulus and internal friction were obtained for the W:Cu = 1:13.5 composite. According to microhardness measurement results, W-Cu nanopowders obtained by SHS method and compacted by HEC technology were characterized by enhanced (up to 85%) microhardness.