High‐Temperature Radiative‐Convective Heat Exchange on the Surface of Glass‐Reinforced Plastics

The results of experimental investigations of heat exchange on the surface of a thermalprotective material — glassreinforced plastic — in the flows of hightemperature gases have been presented. It has been established that the influence of injection on the value of the heat flux does not exceed 10% in the range of variation of gas temperatures 300–2000 K and Reynolds numbers 350–9800.     

Analysis on the Process Parameters’ Impact on the Temperature of Friction Stir Jointing Process of 7022 Aluminum Alloy

Strength of Materials - To better explore the influence of friction stir jointing process parameters on temperature field distribution in the jointing process, the forces acting on the tool and the...     

Cleaning of the Surface of Silicon Structures in the Technology of Very Large‐Scale Integrated Circuits with the Use of Rapid Heat Treatment

Results of investigation of the quality of cleaning of the surfaces of silicon, silicon dioxide, and aluminum films with the use of rapid heat treatment prior to the application of a photoresist and the influence of such cleaning on the deviation of the linear dimensions of a topological pattern subjected to etching are presented. All the results are considered in comparison to the traditional methods of surface cleaning. The parameters of the elements of very largescale integrated circuits manufactured with the use of rapid heat treatment for cleaning of the surfaces of various thinfilm materials coated on silicon are presented.     

Numerical Analysis of the Influence of Natural Convection on the Process of Condensation of Atmospheric Pollutant Compounds on the Surface of Near‐Ground Plants

Numerical investigations of the process of condensation of deleterious atmospheric impurities on the surface of nearground plants under the conditions of natural convective flows have been carried out. The influence of the latter near the surface of phytocenosis elements on the intensity of the process of condensation has been evaluated.     

Influence of Impregnation on the Thermal Properties of Heat‐Insulating Fibrous Materials

The thermalconductivity coefficient and the specific heat of heatinsulating materials impregnated with inorganic binders have been determined experimentally. The influence of the temperature and the degree of impregnation on the thermophysical properties has been revealed.     

Influence of a Long Stay of the Heat‐Release Surface in Kerosene on the Critical Heat Flux in Boiling in It under Steady‐State and Step Conditions of Heat Release

Results of experimental investigations of the influence of a long stay of the heatrelease surface in kerosene on the first critical density of the heat flux in boiling under the steadystate and step conditions of heat release are given.     

Effects of Heat Treatment on the Transformation Temperature and the Microstructure of Ni-Ti-Nb Shape Memory Alloy

The effects of heat treatment on the phase transformation temperature and the microstructure of Ni-Ti-Nb alloy have been investigated by means of R-T method, TEM and EPMA. With the increase of annealing temperature, cooling rate and ageing temperature, the Ms temperature increases. TEM observations show no new precipitated phase was found in the B2 parent phase after heat treatment, but EPMA shows the content of Ni (or Ni/Ti ratio) in the B2 matrix changed. The main reason for the change of transformation temperature lies in the change of the matrix composition (or Ni/Ti ratio) with the variation of heat treatment procedure.     

Influence of the Atomic Mass of a Plasma‐Forming Target on the Parameters of Laser‐Emission Discharge

A study has been made of the influence of the atomic mass of the material of a plasmaforming target on the characteristics of a laseremission discharge developing under the action of Ndlaser radiation on the target. It has been shown that the atomic mass substantially affects the efficiency of conversion of the energy of laser radiation to the energy of a quasistationary electric current; the behavior of the dependences of the load power on the atomic mass of the target substance is different for high vacuum and for resonance pressure and it is not related to the regime of development of the discharge.     

Modeling of the Temperature State of Large‐Size Space Structures

A procedure of modeling of the temperature state of largesize space structures is considered. Results of modeling of the temperature state of a truss structure, the reflector of a reflectortype aerial, and the concentrator of a solar power unit are reported.     

Influence of Ageing Heat Treatment on the High Cycle Fatigue of an 8090 Al-Li Alloy

Fatigue lives for the smooth and notched specimens of 8090 Al-Li alloy jn the different ageing conditions have been studied. For the smooth samples of 8090 alloy the artificial ageing results in an increase in fatigue life in comparison with natural ageing. On the contrary, the notched specimens of 8090 alloy in the naturally aged condition show higher fatigue life than in the peak-aged. The exposure to either the peak-aged or naturally aged leads to superior fatigue properties of Al-Li alloy to the traditional high strength aluminum alloys of 7075 and 2024, especially in the latter aged condition. In all ageing conditions, i,e. naturally, under-, peak- and over-aged, the peak-aged 8090 alloy displays the highest fatigue life and the over-aged material has a minimum value at the same stress amplitude. The difference in fatigue life is mainly attributable to the size and distribution of strengthening precipitates as well as the wide of precipitate free zones (PFZ's) along grain boundaries.     

Effects of Process Parameters on the Temperature Field in Ti-6Al-4V Alloy Blade Precision Forging Process

Blade precision forging is a high temperature and large plastic deformation process. Process parameters have a great effect on temperature distribution in billet, so in this paper, by taking a Ti-6Al-4V alloy blade with a tenon as an object, the influence of process parameters on the temperature distribution in precision forging process was investigated using 3D coupled thermo-mechanical FEM （finite element method） code developed by the authors. The results obtained illustrate that： （1） the gradient of temperature distribution increases with increasing the deformation degree; （2） with increasing the initial temperature of the billet, the zones of high temperature become larger, and the gradient of temperature distribution hardly has any increase; （3） friction factors have little effect on the distribution of temperature field; （4） with increasing upper die velocity, temperature of the billet increases while the temperature gradient in billet decreases. The results are helpful to the design and optimization of the process parameters in precision forging process of Ti-alloy blade.     

Influence of Surface Nano-structured Treatment on Pack Boriding of H13 Steel

In order to lower the boriding temperature of hot work steel H13, method of surface mechanical attrition treatment （SMAT）, which can make the grain size of the surface reach nano-scale, was used before pack boriding. The growth of the boride layer was studied in a function of boriding temperature and time. By TEM （transmission electron microscopy）, SEM （scanning electron microscopy）, XRD （x-ray diffraction） and microhardness tests, the grain size, thermal stability of the nano-structured （NS） surface and the thickness,appearance, phases of the surface boride layer were studied. Kinetic of boriding was compared between untreated samples and treated samples. Results showed that after SMAT, the boride layer was thicker and the hardness gradient was smoother. Furthermore, after boriding at a low temperature of 700℃ for 8 h, a boride layer of about 5 μm formed on the NS surface. This layer was toothlike and wedged into the substrate, which made the surface layer combine well with the substrate. The phase of the boride layer was Fe2B. Research on boriding kinetics indicated that the activation energy was decreased for the treated samples.     

Influence of Moderate Temperature Treatment on Thermal Cycling Behaviour and Mechanical Properties of the CuAINiMnTi Alloys

The influence of moderate temperature treatment after quenching on thermal cycling behaviour andmechanical properties of the CuAlNiMnTi shape memory alloys have been investigated.It is shownthat there will be α phase precipitation in the alloy when it is subjected to quenching followed bymoderate temperature treatment at 600℃.The precipitation of α phase can suppress NiAl-basephase precipitation during subsequent thermal cycling,therefore the stabilization of transformationtemperature during thermal cycling can be achieved.The suitable amount of α phase precipitationcontributes to the improvement of mechanical properties of the alloy by changing the fracturemorphology.     

STM Study on the Surface Relief and Mechanism of Bainite Transformation

Scanning tunneling microscopy (STM ) has been first employed to study the surface relief accompanying bainite transformation in a Fe-2.17C-12.18Cr-0.31Si-0.26Mn (wt pct) steel. With the exclusive vertical resolution of STM, we observed that the surface relief associated with bainite is a group of surface reliefs related to subplates, subunits and sub-subunits. As a whole, the relief group is in a tent shape, not of invariant plane strain (IPS) type, which is obviously different from that of martensite, and implying that bainite is not formed by shear mechanism. The fine structure of bainite in Fe-1.0C-4Cr-2.0Si (wt pct) alloy has also been studied with STM and TEM. It is found that the bainite plate is composed of subplates, subunits and sub-subunits. On the basis of the fine structure inside a bainitic ferrite plate observed under STM, a sympathetic-ledgewise mechanism of bainite formation is proposed     

Effect of Heat Treatment on the Corrosion Characteristics of Al-Li Alloys

Experiments were conducted to study the general room temperature corrosion characteristics of heat-treated and non-heat-treated Al-Li alloys with different Li compositions. Corrosion rate was measured using both the polarisation method and the weight-loss method. It was observed that the samples with higher Li content had lower corrosion resistance than those with lower Li content. Moreover, for all the specimens tested, it was fOund that heat treatment at 180℃ for 2 h (for the purpose of precipitation hardening) severely reduced the corrosion resistance,whereas heat treatment at 180℃ for 6 h significantly increased the corrosion resistance.     

Process of Cooling of a High‐Temperature Two‐Phase Flow

A technique and a design of a transducer for measuring the enthalpy of twophase flows using the thinwall method have been developed. Working formulas for calculating the heat capacity and the enthalpy of a gas flow are substantiated. Results of a test of the transducer in hightemperature flows of powder gases, including those after the packing of a coolant, are presented. The results obtained show that cooling of powder gases due to an endothermic reaction makes it possible to decrease the enthalpy flux by a factor of 5 and the temperature by a factor of 2.     

Influence of the Random Structure of an Initial Material on the Processes of Self‐Propagating High‐Temperature Synthesis in Thin Films

Numerical simulation of the process of selfpropagating hightemperature synthesis in twodimensional systems, the physical prototypes of which are thin films, has been performed. The emphasis has been on consideration of the heterogeneity of the system and randomness in the spatial arrangement of its different components. It has been found that taking into account the randomness factor, all other things being the same, leads to a substantial change in the basic characteristics of both the combustion process (for example, of the wave velocity) and the end product of synthesis. It has been demonstrated that, first, the critical level of external heat loss decreases significantly as compared to the case of a uniform distribution of the reagents and, second, this characteristic undergoes an abrupt increase in the vicinity of the reagent concentration corresponding to the percolation threshold for the lattice used in simulation. A qualitative comparison of the simulation results with experimental works has been carried out.     

Heat and Mass Transfer in Condensation of Harmful Air‐Polluting Substances on the Phytocenosis Surface

A mathematical model for the condensation of harmful airpolluting substances on the phytocenosis surface is formulated. Results of a numerical study of the problem of heat and mass transfer are presented. The temperature and concentration fields, the time dependence of the condensation rate, and the distribution of the condensate film over the phytocenosis surface are obtained.     

Influence of Process Parameters on Cu–Fly Ash Composite by Powder Metallurgy Technique

In this study influence of compaction pressure, sintering temperature, and sintering time on mechanical and wear behavior of the fly ash reinforced copper-based composites are analyzed. The composites were prepared by powder metallurgy (P/M) technique with copper as matrix, 5 and 10 wt% of fly ash as reinforcement. The green compacts were prepared at three different pressures such as 350, 400, and 450 MPa. The prepared green composites were sintered at 700, 800, and 900 °C for the time period of 30, 60, and 90 min, respectively. From the results it is observed that when the process parameter increases the density, hardness, compression strength, and wear resistance increases.