High strength with loss of ductility has been demonstrated a limitation of engineering utility in bulk nanostructured materials. Y.M.Wang et al reported nano-Cu with bimodal structure obtained by cryo-rolling at liquid nitrogen, which possess excellent tensile ductility without obvious loss of strength. It suggests micrometer-sized grains with some fractions embedded in nanostructured matrix, namely bimodal structure was possible to be an effective route to eliminate the loss of ductility. On the other hand, Chokshi et al founded complete different result in annealed electrodeposition nanometer crystal nickel,which is the same as the conditional recognition that the mixcrystal structure would deteriorate mechanical properties gravely.But as a typical kind of mixcrystal structure,bimodal improve the properties,which show that we should research the different two grain size’s parameters deeply.And if we want to get the point,first job is to prepare the bimodal that structure’s parameters is controllable.In this paper,it establish a new method to get the bimodal that structure’s parameters is controllable successly in Cu-Al eutectoid system alloy by composition design + eutectoid-phase-transformation treatment + severe plastic deformation + annealing.Investigate the relation of structure and properties preliminary and verify the bimodal’s feasibility.Results show that: we get the bimodal structure of micro grain pro-eutectoid phase+ultra grain-refining eutectoid matrix by ECAP+annealing processing chains in Cu-Al eutectoid system alloy; and the bimodal does improve the ductily, tensile ductility is greatly improved without much loss of strength.And the ductily increases with the pro-eutectoid’s volume proportion and annealing temperature’s increasing, At the condition of pro-eutectoid phase’s volume proportion is 40%,ductility would be better when the pro-eutectiod phase’s distribution is more uniform and litter,material would get the high strength and high elongation.
Post about "Heat treatment"
The effect of heat-treatment on milling yield, nutrition compositions, viscosity properties of oats was explored, and the effect of extruder operation parameters on the qualities of oat extrudate was researched. The purpose of this research was to provide experiment data and technology support to develop the milling and extrudate of oats.Oats (Avena Sativa L.) samples were milled by a Chopin experiment mill type CD-2 into four streams, namely break flour(BF), midding flour(MF), fine bran(FB), and coarse bran(CB)after different heating treatment such as air-heating at 140℃,155℃,170℃respective or far-infrared heating at 200℃,220℃,240℃respective. The flour yield, the nutrition compositions, including protein, fat, and fiber contents of four streams and the viscosity properties of BF, MF and Oats Flour were investigated. The effect of extruder operation parameters (barrel temperature, material moisture and feed rate) on the system parameters (pressure and torque)of extruder, and product properties (specific volume, crispness, hardness, color, water absorption index, water solubility index, etc.) of extrudate was studied during the oat extrusion by orthogonal experiment method(L9(34)) with Oats Flour. A comprehensive evaluation of the extrudate was obtained by using factor analysis. The operation parameters of oats extrusion were opitimized and validated.Conclusion:(1)After heat-treatment, the milling yield of BF and MF of oats increased significantly. The total milling yield of four components was 18.18% higher than that of oats without heat-treatment. The protein decreased from CB, FB , MF, to BF. The fat of BF reduced significantly. The fiber of FB and CB raised significantly.(2)After heat-treatment, the average gelatinization temperature of BF, MF and Oats Flour were decreased significantly, which were lower than that of oatS without heat-treatment. Their peak viscosity; final viscosity and hold viscosity increased both under air-heating (140℃,155℃) and far-infrared heating (200℃), relative to non-treated samples. With the temperature of heat-treatment increasing gradually, their viscosity properties decreased. Their peak viscosity; final viscosity and hold viscosity at air-heating (170℃) and far-infrared heating (220℃) were lower than those at air-heating (140℃) and far-infrared heating (200℃).(3)The effect of qualities of extrudate of oats decreased from extrusion temperature, feed rate, to mass moisture. Under the laboratory condition, the optimal extrusion parameters of the test was as follow. The barrel temperature was 165℃. The mass moisture was 20%. The feed rate was 30g/min, and the screw speed was 120r/min. Validation experimentation showed that those operation parameters were stably and feasible.The result shows that heat-treatment has significant effect on the milling yield, nutrition properties, and viscosity properties of Oats Flour; nice extrudate of oats by technology design and optimization of extrustion could be produced.
With the rapid development of new technologies on aviation, spaceflight and micro-electronics,the request of general properties to Cu-matrix is getting higher and higher.Due to have the special properties of both metal and ceramics, MAX compound has became the hotspot of research inland and overseas as the wild phase.This work mainly studies the fabrication and heat-treatment properties of Cu/Ti3AlC2 composite.The missions of this work are:（1）,To fabricate high purity of Ti3AlC2 powders and （20～60vol.%） Cu with Ti3AlC2 composite bulks.（2）,The structure and properties of Cu/Ti3AlC2 of different volume ratios.（3）,The heat-treatment of 30Cu/Ti3AlC2 and 50Cu/Ti3AlC2.（4）,The influence to materials made by heat-treatment.The results show that high purity of Ti3AlC2 powders can be obtained by pressureless sintering the proper mole ratios of Ti,Al,Sn,C powders at 1450℃for 10 minutes.Also,the compact Cu/Ti3AlC2 composite can be obtained by hot pressure sintering the proper ratios of Cu and Ti3AlC2 powders at 1150℃and the maximal pressure is 30 MPa.Due to the firm combination between the accumulative lamination of TiCx and Cu（Al） alloy, and spacial network configuration formed by Cu（Al）,（40～60vol.%） Cu/Ti3AlC2 possess excellent general properties.However, （20～30vol.%）Cu/Ti3AlC2 products intermetallic compound,their general properties decrease.Heat-treatment can improve the properties clearly to 30Cu/Ti3AlC2. After 950℃during 8 hours heat-treatment,the alloy has dissolved adequately and improved material’s interior fabric,so the material’s general properties are enhanced.On the contrary, heat-treatment can’t improve the properties of 50Cu/Ti3AlC2.Though the heat-treatment after 1500℃has made the the TiCx layers out, the TiCx grains have grown up clearly from 150 nm before heat-treatment to severalμm. The material’s general properties are reduced.The innovation of this work is a primary research about heat-trearment of Cu/Ti3AlC2,and has blazen a way in fabricating high strength and high conductivity copper/ceramic composite.
The urgency of solar cell industry is to enhance the conversion efficiency at limited cost.And solar cell is a ‘one electron-hole pair for one photon’ device, which means waste ofexcess energy in the ultra-violet region. Quantum cutting, converting one high energy photoninto two or more photons, is likely to improve the efficiency limit to 37%, after detailedcalculation.However, most works focus on fluoride phosphors or ceramic materials. Those materialsare of great rigidity and hard to shapen. The high cost of sophiscated manufacture processlimites their application. While, rare earth doped oxy-fluoride glass-ceramics exhibit both thecrystals’ excellent optical property and the glasses’ easy fabrication property. Fewinvestigations are reported on QC in glass-ceramics.We report on near infrared QC in rare earth doped glass ceramics. Precipitation of BaF2nano-crystals under appropriate heat treatment condition is confirmed by XRD and HRTEManalysis. We choose RE3+ ions (Tb3+, Pr3+ and Tm3+) to co-dope with Yb3+ion, since theenergy of 5D4→7F5 transition of Tb3+ion, the energy of 3P0→3H4 transition of Pr3+ion and theenergy of 3H6→1G4 transition of Tm3+ion are of twice the energy of Yb3+ion’s 2F5/2→2F7/2transition. After excitation, the energy transfered from sensitive ion to Yb3+ ion result in itsNIR emission and this process is the typical quantum cutting phenomenon.We employ PL spectra and decay curve to find how concentration (Yb3+ ion), heattreatment condition affect the energy transfer process. We also calculate the lifetime of RE3+emission, the energy transfer efficiency （EFE） and the efficiency of QC.We find adding more Yb3+ ions can speed up the ET process. For example, within theTb3+, Yb3+ codoped system, as the concentration of Yb3+ ions increases, the lifetime of Tb3+emissioncentered at 542nm decreases and the QC efficiency increases to 145%. The QCefficiency of Pr3+, Yb3+ system and Pr3+, Yb3+ system rises from 151% to 191% and 101.6%to 135.4%, respectively.The heat treatment condition affects the QC effect within RE3+, Yb3+ions by changingthe phase of BaF2 crystals. As the temperature rising and time prolonged, the size of crystalgrow and more rare earth are incorporated into nano-crystals. As we know, crystalcircumstance with low phonon energy is beneficial to energy transfer and transition emission.In the Tm3+, Yb3+ system, as the temperature rises from 640℃to 740℃, the crystal size increases from 25nm to about 70nm, the lifetime of Tm3+ ion decrease from 21.41μs to 7.11μs,while the QC efficiency increases from 138.5% to 179.6%.
Design and Application of Computer Management and Control System for Conventional Heat Treatment Process
Heat treatment is one of important processes in the manufacture of mechanical parts and equipments. Appropriate heat treatment is advantageous to develop strength potential of metals and performance of mechanical parts. Automation of heat treatment production is paid more attention along with increasing requirement of performance and reliability. With the development of computer, the application of heat treatment automation is widespread. The integration, intelligent and network management of heat treatment production can be realized with the help of information technology.By heat treatment process management, the quality of process planning can be improved, and product seedtime can be shortened. The temperature of heat treatment procedure is measured and controlled in a way of real time according to fuzzy control theory, and the production record is added to database, which can improve heat treatment quality, strengthen the quality backtracking. The two sub systems are integrated to improve efficiency, manage information effectively and heighten competitive capacity.The common problems in practical heat treatment process of heat treatment enterprises are investigated. Based on the practicality for customers, a set of software system applied to heat treatment process is developed by Visual Basic 6.0 and SQL Server 2000. The main purpose is to designing process management and control system, summarized as follows:1. Based on relative literatures and ISO 9000 series standards about the particular requirements of managing and controlling production quality files, process files and records are managed effectively. By information technology, heat treatment database is designed to aid process planning.2. The structure of host computer and AI controllers is introduced to design heat treatment control system. The control and measurement of heat treatment furnace is realized via communication protocol. The system can control temperature precisely and record the production data exactly and detailedly.3. Integration of the two systems reduces workload of the operators and improves work efficiency remarkably. The whole process is managed and controlled effectively, total quality management for heat treatment production process is carried out.
Along with the fast development of the transportation industry, the equipments also turn to the direction of large-scale, high speed, the heavy load, and the high security. So the standard of the operational-performance of the friction material is being set more and more higher. Recently, researchers are turning their attention to a new type of composite material-interpenetrating phase composites. This combination gives full play to the advantages of both the reinforced phase and the matrix phase by interpenetrating and mutual supporting, therefore brings the outstanding physical, chemical and mechanical performance.Leading Cu into the SiC carcase to produce the 3D-Meshy SiC/Cu composite material. Some researches of this material on the mechanical property, the interface reaction, the influence of heat treatment and the friction and wear property were did. The results are as follows:(1) Bending strength of the 3D-Meshy SiC/Cu composite material reached 225.9MPa, compression strength reached 199.9MPa, and tensile strength to 19MPa. Interpenetration of the SiC reinforced phase and the Cu matrix phase resulting the mutual supporting when the load is added, so the mechanical property improved a lot.(2) Interface reaction existed during the casting procedure of the 3D-Meshy SiC/Cu composite material. The interface reaction mainly divides into three steps:(1) SiC decomposed into Si and C; (2) SiC and C produced by the SiC reacted with the Cu matrix, resulted variety interface products; (3) solid phase diffusion. The main interface products include Cu4Si、C、TiC、V-C、Cr-C and Cr-Si compound. There are mainly four interface reaction region from the SiC framework to Cu matrix:the first region include Cu4Si、C、Ti-C and Cr-C compounds; The second region is the transition zone of the first and third region; The third region mainly are TiC and V-C, and the fourth is Cr-Si compounds; The third and fourth regions are at the forefront of the interface reaction region, which blocked the atoms diffusion of the two sides of interface, and restrained the interface reaction.(3) After the 3D-Meshy SiC/Cu composite material was heated at 700℃and held for 30、60、90、120min, no new interface compounds or phases were detected. The heat treatment made no big influence to the other element’s distribution of the interface region,except changing C’s distribution in the first region, as the increase of the heat treatment time, large-scale graphite phase began to disappear and turned to dispersely distributed particles; Cu has oxidized gradually into Cu2O and CuO during the heat treatment process; After the heat treatment, the Cu substrate’s grain size increased, and the density of the twin crystal also increased; show The diffusion coefficient D of Cu was 2.76×10-14 m2·s-1 calculated through the Fick diffuse law. (4) Simulation of braking experiment on passenger vehicle has been carried out by using the 3D-Meshy SiC/Cu as Static ring and cast iron as moving ring. The results showed that: with the increase of the rotational speed, the average friction coefficient and acceleration reduced while the braeking time and braking distance increased. with the increase of the pressure, the average friction coefficient、braking time and braking distance all reduced while the acceleration increased; The abrasion mechanism in the braking process mainly is abrasive wear, while follwing with some additive wear, and, the material transport from cast iron ring to 3D-Meshy SiC/Cu ring occured. The 3D-Meshy SiC was able to support the load applied onto the sliding surface and restricted the plastic deformation and high-temperature softering of the Cu matrix, thus it showed nice friction and wear properties.
15CrMoR steel is low carbon and dilute-alloy pearlite steel which exhibits good integrated mechanical properties. Hot simulation and experimental rolling are used to simulate the real rolling technics of 15CrMoR pressure vessel steel. The main works are involved as follows:(1)When single press test is taken, the influence of the deforming temperature, deforming degree and deforming rate are researched, and the mathematical model of resistance of deformation is established. The behavior of dynamic softening of the steel in austenitic area is also researched. The activation energy of dynamic recrystallization is 346.9 kJ/mol.(2)The heat expansion method is taken to make the CCT curves under deformed and undeformed condition. The results show that deformation makes CCT curve move leftward and upward.(3)Based on the thermal simulation experiment, the rolling technology of the tested steel is researched by the hot rolling test in the laboratory. The experiment results show that the strength is increased with the decrease of finish rolling temperature. The results also indicate that the cooling rate after rolling can affect the properties.(4)The effect of the heat treatment on the micro structures and properties are analyzed. The results show that normalizing temperature has an evident influence on strength and toughness. When 940℃,15CrMoR steel has good strength plus good toughness. Normalizing cooling rate is also a crucial factor because it can change the microstructures of the steel. There is no temper brittleness within 15CrMoR steel. The relationship between the short time tensile strength and the long-term rupture strength is established. Working for 100,000 hours under the condition of 550℃high temperature, the long-term rupture strength of 15CrMoR steel is 71 MPa.(5)It is suggested that the appropriate industrial producing way is as follows:rough rolling temperature is 1100℃, finish rolling temperature is 860-850℃, normalizing temperature is 940℃, normalizing heating time is 2.5min/mm and temper temperature is 690℃.
With the fast development of shipbuilding industry, the demand of high strength hull plate is more and more, and it brings lots of chance to the China iron and steel industry. Many new medium plate production lines have been built to supply the demand. The subject was investigated on high strength hull plate steel, the composition design according to the fundamental of Low-Carbon High-Manganese and Nb, Ti-microalloyed. Applyed three kinds of product technics in rolling processing, In order to get super performance of strength and toughness heat-treatment the rolled plate. The main studies are shown as follows:1. CCT curve is measured by hot simulation experiment, the influences of cooling speed to ship plate steel are gained by analyzing these deferent parameters. The mensuration of the relation of growing up austenitic and time and the ralation of growing up austenitic and temperature. Then feasible process parameters are defined by laboratory data.2. According to the results of hot simulation experiment, optimized the process technologies of high strength hull plates. Analyze the different processing parameters of the three different thickness plates. Selected three kinds of thickness (20mm,30mm,40mm) And applyed three kinds of product technics in rolling processing,found that the rolling types of CR and TMCP of tensile and impact are super than AR.3. The relation between processing and properties for EH36 of heat treatment is analysed, which was found is with the increase of heat temperature and time of heat preservation, the impact properties are best than before, but the opposition of the tensile properties have not notability improve.4. According to the industrial trial manufacture, the technics of TMCP can be applied to meet the requirements of Association Classification Societies.5. According to the fundamental of Low-Carbon High-Manganeseand Nb-microalloyed designed the chemical constitutions of EH36 which satisfied the needs of factory, and the high strength hull plate super performance are produced. The technics of CR:the heating temperature is 1200℃;and the opening rolling is 1100-1150℃;the second opening rolling 860-910℃; the finishing temperature of finish rolling is 810-850℃; then adopted cooling under the air or water. Cooperated with heat treatment, attained to eligibility high ship plate.Appled the normalizing technics for thick high ship plate, the better heat temperature is 910℃and the time of heat preservation is 1.7-2min/mm.
In this dissertation, the preparation of anodic aluminum oxide（AAO） membrane with a support, the characterization of membrane’s pore structure, the flexibility and permeability have been studied. The morphology and structure of the pores of AAO membrane were determined by means of Scanning Electron Microscopy （SEM） and X-ray Diffraction（XRD）. The flexibility and corrosion resistance are studied by electrochemical methods and heat treatment. the flexibility of porous alumina membrane is analyzed by Electrochemical Impedance Spectroscopy （EIS） , The pores size, distribution, porosity are characterized by bubble point test and boiling method.The membrane of AAO prepared by electrochemical anodic oxidation process is a water-included membrane with poor flexibility. After heat treatment, the flexibility and corrosion resistance have been obviously changed. The effects of time and temperature of heat treatment and the electrolyte component have been investigated. The results show that the primary factor which effected flexibility of AAO is the electrolyte component. About the AAO membrane in phosphoric acid, the higher temperature of the heating process, the better flexibility. The flexibility of oxide membrane will not change when it arrived at a certain temperature, and it will be destroyed when been over-heated. The flexibility of oxide film is related to the time of heating. For AAO membrane in sulfur acid and oxalic acid, the flexibility of membrane has been destroyed obviously, there are many defects of the film after heated treatment. The polarization curve of films indicates that the corrosion resistance of AAO membrane is improved after been heated in phosphoric acid.At room pressure, the EIS of AAO membrane in H2O/H2O, 0.1MNaCl/H2O, 0.1MNaCl/0.1MNaCl solutions shows that practical systematic circuit of porous alumina film can be expressed with （RC）R（QR）R（RC）. The EIS analysis of AAO membrane in phosphoric acid show the plots of Nyquist are a Warburg impedance spectroscopy obviously in NaCl/H2O system. It has the characterization of pervasion. In Bode spectroscopy, the magnitude of impedance is decreased gradually with the increasing of permeability time; the change of the impedance with the frequency has the similar process for the film in the above three solutions, the impedance value is decreased gradually with the time increasing, and the value is comparatively lower in the high frequency area. During this period, the qualitative analysis of permeability of AAO membrane is feasible in phosphoric acid by means of EIS. The EIS is not characterized the permeability in sulfur acid and oxalic acid solutions.The characterization of the AAO membrane is an important index for evaluating the quality and application field of the film. The pore structure, pore size distributing frequency, average pore diameter and maximal pore size can be determined by means of bubble point test. The porosity of alumina membrane is measured by boiling method and SEM, and the reason for the difference of the two methods is discussed.
In this study, the microstructures of as-deposited, as-extruded and heat treated high-strength 7055 Al alloy prepared by spray forming process were analyzed by using optical microscopy（OM）, （XRD）, （SEM）, （TEM）, （EDS）, and evolution on the microstructures of high-strength 7055 Al alloy under various conditions was summarized, which could provide scientific basis for optimization on the parameters of spray forming ,hot deformation and heat treatment process , to improve the mechanical properties of the aluminum alloys. The results showed as follows:A large-scale 7055 Al alloy billet by spray forming with a size of Φ260×1600 mm was successfully prepared by fully automatic controlled reciprocating spray forming technology. The surface of the billet was good and it’s satisfiable to turn 23mm thickness. The microstructures of as-deposited billet are composed of some equixed grains with no distinct difference ,and the sizes of grain are between 30μm and 50μm. The billet has no macro-segregation structure and its density gets up to 98.2% . The second-phases in the microstructures of as-deposited billet are composed of reticular phases of grain boundary and transgranular needle-like phases and transgranular near-spherical phases and a few blocky phases . There were lots of Cu and Al in triangular grain boundary and the MgZn2 dissolved the Cu and Al elements, and formed the Mg（Zn,Cu,Al）2 phase and the transgranular precipitated phases were MgZn2 . The content of Al2CuMg is too little to determine .After the heat treatment, the grain boundary second-phases of as-deposited materials reduced, even vanished and the grain boundary stricts and the grains were unified closer and the transgranular needle-like phases vanished and the transgranular mass was distributing the nanometer level precipitated phases. The result of EDS analysis indicates that the content of Mg, Cu and Zn from original 12.97%, 21.60% and 30.99% drop to 2.18%,2.18% and 11.05% in second-phases of triangular grain boundary. After the extrusion, the primitive grain boundary of as-deposited material vanished and the reticular phases was disrupted and the grain broke up. The microstructure was more compact and more tiny crowded second-phases precipitated. As the extrusion ratio increases, the distortion degree of grains is bigger and the breaking of grain is fiercer and the quantity of grain boundary are more and then precipitated phases are more during heat treatment, thus strength increases correspondingly, but when the extrusion ratio increases to certain value, the ability of dispersion strengthening and fine grain strengthening achieves the apex and the mechanical properties no longer increase. The TEM analysis indicates that the grain size of T6 material with an extrusion ratio of 6 is about 5μm, the tiny subgrain formed near the triangular grain boundary. As well as the discontinuous and continuous precipitated phasesη（MgZn2） precipitated in the triangular grain boundary and the tiny disperse GP area and transitional phasesη’ （MgZn2） existed in matrix.The longitudinal and transverse tensile strength of as-deposited materials of 7055 aluminum alloys were 222 MPa and 252 MPa respectively . And the ultimate tensile strength of as-deposited materials after T6 heat treatment got up to 500543 MPa , which indicated that there were few defects in the as-deposited billets produced by fully automatic controlled reciprocating spray forming technology. After deformation with small extrusion ratio, the billets could be fully densified. As well as the ultimate tensile strength of the large-scale materials at T6 state was increased to 745 MPa , and the elongation was 12.8%.