- Volume 44,Issue 6,2014 Table of Contents
>综述
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2014, 44(6).
Abstract:
With the development of modern information technology, the weapons and equipment environment increasinglycomplex. Stealth technology is becoming more popular in the weapons areas for the aims of hitting the enemytargets and improving the operational capability. The radar stealth technology is an important research directionand researchers put more attention for radar stealth technology. This article introduces the research status and absorbingtechnology of absorbing structure composite materials. >计算材料学
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2014, 44(6).
Abstract:
Since the adhesive is located between two layers of material, the internal structure of the adhesivedebonding process is often difficult to detect. In this paper, three kinds of adhesives’ plate samples and the Ushapedsamples were made, the mechanical properties of tensile and shear state were tested and the correspondingstrain energy release rate were calculated. VCCT technology was used, the fracture and debonding area were predefined,the cracking and debonding process of the adhesive in a tensile and shearing state were simulated. By contrastingthe maximum stress and maximum displacement obtained by numerical simulation and experiments, it was indicatedthat the VCCT technology could effectively predict fracture critical load of these three adhesive, and show that thismethod could obtain the expansion process of debonding area. This laid a good foundation for the study of complexstructures’ debonding process. -
2014, 44(6).
Abstract:
Calculation analytical method is applied to aluminium liner carbon fiber winding composite gas cylinderduring elastic-plastic process under inner pressure, autofrettage pressure is obtained from inference. The rationalityof the calculated results is verified through hydrostatic strain test and fatigue test method. By comparative analysis ,the calculation method can be applied to similar structure gas cylinder autofrettage pressure calculation in the future. >新材料新工艺
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2014, 44(6).
Abstract:
An extensive investigation has been carried out on the friction stir welded lock joint consisted of a2219MCS ring and a 2219C10S barrel, and the effect of the FSW pin length and AS location on the Hook defect, mechanicalproperty and fracture mode of the lock joint has been systematically analyzed in this paper. As the results indicatedthat, there is a hook defect located in junction of the assembly interface and nugget zone, and the warping rateand the migration amount of the junction when 2219C10S barrel located in AS location is greater than 2219MCS ringlocated in AS. And the migration amount of the junction increased with the FSW pin length. The results of the tensiletests indicated that the mechanical performance of the lock joint with the 2219MCS ring located in AS is better thanthe 2219C10S barrel located in AS, and the mechanical properties reduced gradually with the increase of the FSW pinlength. As analyzed, the morphology of the hook defect and the migration amount are the main reasons for the changeof the mechanical properties with the AS location and FSW pin length. The optimized investigation results show thatthe room temperature mechanical strength can be up to 300 MPa, the low temperature strength is 370 MPa, and theductility is all more than 3. 5%. The tensile failure mode of the FSWed lock joint is closely related to the AS locationof the 2219MCS ring or 2219C10S barrel. -
2014, 44(6).
Abstract:
Diamond-like Carbon (DLC) films was deposited on the bearing steel by closed-filed unbalanced magnetronsputter technique, and CrN films was deposited on the bearing steel by cathodic arc ion plating. The tribologicalperformance of DLC and CrN films in the fully formulated engine oil (CF-4, 15W/40) lubrication conditions were investigatedon a SRV-IV tribo-meter. The effects of load and temperature on the friction coefficient and wear rate wereanalyzed. The results indicate that the friction coefficient of two kinds of films decreases with increasing load under oillubrication condition. DLC solid/ liquid synergistic lubrication have excellent tribological properties compared to the liquidlubrication. Thin tribofilm on the interface caused by the tribochemical interaction between CrN films and additivesin the CF-4 engine oil decrease the friction coefficient under high load and high temperature. In addition, the wear resistanceof the CrN films was improved as oxide layer formed on the surface at higher temperature. -
2014, 44(6).
Abstract:
In this work, hot corrosion behavior of Ni-20Cr-18W based superalloys at 900℃ has been investigated.The alloy corroded in 75% Na2SO4 +25% NaCl mixture molten salt has been analyzed by optical microscope, X-ray diffraction, scanning electronic microscope and energy sispersive X-ray analysis. Results show that the Ni-20Cr-18W based superalloy represents basic dissolution model. The corrosion front goes ahead as a plane into the matrixof alloy without selective corrosion behavior. Most of outcomes in the outer corrosion layer are NiO and Ni3S2. The alloysurface loses protective oxide layer and the outcomes increase the corrosion rate. The high thermal corrosion rate ofalloy can be ascribed to the tungsten element and the corrosion between second phase particles and matrix. -
2014, 44(6).
Abstract:
The pyrolysis condensation of zirconium-containing pitch was studied by means of TG/ DTG and wascompared to pitch. Results show that the pyrogenation reaction of pitch contain zirconium was similar to baselinepitch,but initial pyrolysis temperature of zirconium-containing pitch was higher than baseline-pitch and viscosity wasgreater. The initial pyrolysis temperature Ti and final pyrolysis temperature Tm increased with increasing the heatingrate and the peak of DTG curve became acute and moves to the high temperature orientation. The activation energy ofzirconium-containing pitch and based-pitch is close, which indicated that the reactive activity had no obvious changeunder the current content of zirconium. -
2014, 44(6).
Abstract:
Nanometer titanium dioxide particles have been prepared by the sol-gel method,in which butyl titanateas precursor,ethylene glycol as a chelating agent. And the glycol of titanium salt concentration,pH value,temperatureon the influence of the particle size titanium dioxide were studied. Moreover,the structure and morphology of nanometertitanium dioxide particles were characterized by infrared spectroscopy and SEM. The experimental results showthat uniform size distribution of nanoparticles titanium dioxide can be prepared by sol-gel method. Using ammonium nitratecould effectively prevent the titanium dioxide nanoparticles reunion. When pH value is 2 to 3, the temperature is20℃ to 40℃,the concentration of titanium salt of ethylene glycol in the acetone is 0. 03 M,the diameter of titaniumdioxide nanoparticle is 150 nm;the concentration of titanium salt of ethylene glycol in the acetone is 0. 05 M,the particlesize is 240 nm;and when the concentration of titanium salt of ethylene glycol in the acetone is 0. 07 M,the diameterof titanium dioxide nanoparticles can reach to 600 nm. -
2014, 44(6).
Abstract:
A silicon-containing arylacetylene resin( PSA) was modified by blending bis(3-acetylenephenyl)dimethylsilazane(SZ) synthesized by an aminolysis procedure. A series of test methods were used to investigate therheological behavior, curing reaction,thermal stability,flexural and dielectric properties of PSA/ SZ. The mechanicalproperties of quartz fiber reinforced composites were also measured. The results show that with the increase of SZ, theviscosities of PSA/ SZ resins decrease remarkably, the flexural strength of PSA/ SZ resin increases by 62. 7%, theflexural strength and interlaminar shear strength of quartz fiber reinforced PSA/ SZ resin composite increase by 18. 7%and 60. 4%, respectively. -
2014, 44(6).
Abstract:
By taking preform weaven with radial carbon rods as reinforcement phase, C/ C composite was preparedby impregnation and carbonization process using coal tar pitch as matrix precursor, and its bulk density is 1． 50g/ cm3. The distribution of density was tested by CT, and the distribution of pores were analyzed by means of opticalmicroscope and mercury intrusion method. The results showed that the density of outer fringe of body is the highest,and the density decreased from outboard to center along radial of the body under the technological conditions of pitchimpregnation and carbonization. The density distributed evenly along the direction of identical circle taking body centeras reference point. The porosity of the body increased from outboard to center along radial of the body. The porevolume ratio of macropores and mesopores increased from outboard to center along radial of the body, on the contrary,the pore volume ratio of micropores decreased from outboard to center along radial of the body . -
2014, 44(6).
Abstract:
This article elaborates on the integral forming in the autoclave of large size multi lattice structured compositewith particular emphasis on the optimistic design of overlay processing and assurance of forming pressure. It isproved by engineering practice that the ware preforming of such frame can be realized by breaking down the overallstructure into multi technique units, in which unit overlay is first completed, followed by rest of overlay after matchingmolds; and the technique of alternative use of soft and hard abrasives, pressure transmitting of soft abrasives, assuranceof frame geometrical size by hard abrasives, can achieve the integral co-curing molding. The products manufactured canmeet the designing requirements of deviation of shape and position in terms of flatness of upper and lower surface, andits deviation of thickness, content of rubber and product quality can be also controlled within an allowable range. -
2014, 44(6).
Abstract:
This paper introduce a new R602 resin system for room temperature RTM process, which have lowviscosity, high reaction activity and good properties. The resin began to gel at 105℃, to cure at 125℃ and to handlefor better properties at 175℃, the Tg is 178℃. R602 resin system have low viscosity at room temperature and its potlifeis more than 50 hour. The cured resin and composites of R602 resin system also exhibit excellent mechanical propertiesand hygroscopic resistance property. The tensile strength of the cured product is 97. 2 MPa, fracture elongationpercentage is 4. 12%, and flexural strength is 162. 6 MPa. In addition, the SEM reveal that the impregnation of theR602 resin to fiber is very good. -
2014, 44(6).
Abstract:
Mesoporous silica with two-dimensional (2D) hexagonal framework (SBA-15) and worm-hole framework(MSU-J) were synthesized with different silica precursors and it was further employed to modify poly( methylmethacrylate) (PMMA) to form novel SiO2 / PMMA hybrids with lower dielectric constant, higher thermal and mechanicalproperties. The structural feature and physical properties of these materials were studied by XRD, SEM,DSC and TGA. The results manifested that introduction of SiO2 into PMMA exhibited toughening and reinforcing effecton the hybrid materials. The dielectric constants of the hybrid materials can be reduced from 2. 91 of the pure PMMAto 2. 73 and 2. 64 by incorporating 4 wt% SBA-15 and 7 wt% MSU-J, respectively. -
2014, 44(6).
Abstract:
Generally, the suppliers of aluminum silicate fiber only offer customers thermal conductivity at a certaintemperature, which make it difficult for engineers to design those insulation structures. In this study, in order toprovid reliable temperature data to finite numerial simulation,an experiment was designed to study the heat-shieldingproperties of aluminum silicate fiber in high temperature environment. It indicates that the heat insulation efficiency ofaluminum silicate fiber is stable with the ability to resist thermal radiation and the numberical calculation results agreedwith experimental data. The study above lays a solid theory foundation for the design of insulation structure. >测试分析
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2014, 44(6).
Abstract:
Seven stud bolts bending two cabins were found fractured after the separation device being static tested.The surface of bolts was done by Dacromet treatment. Observation on fracture surface and analysis of experimentall indicate property of delayed brittle fracture caused by hydrogen embrittlement. Besides the bolt material’ s highsusceptibility to hydrogen embrittlement, the long time wet coating on bolt during testing largely led to the fracture. Analysisindicates that high tensile steel-made item after Dacromet coating treatment is still subject to hydrogen embrittlementfracture that causes serious consequence under tensile stress in circumstance where water and corrosive mediumsuch as Cl, S exists although Dacromet coating treatment effectively prevent the item from hydrogen embrittlementin surface processing period. This conclusion may serve as precaution to those who design and use high tensile steelunder similar circumstance. -
2014, 44(6).
Abstract:
Push-rod dilatometer has been developed for measuring linear thermal expansion coefficients of solidmaterials for thermal expansion from the room temperature to 500℃. The linear thermal expansion coefficients of single-crystal sapphire have been determined using the Push-rod dilatometer. The present data are compared with the datarecommended by the National Institute of Standards and Technology ( NIST), which are in good agreement. Therelative uncertainty in the measurement was estimated to be less than 4% in the temperature range, based upon thedata of single-crystal sapphire. -
2014, 44(6).
Abstract:
Three dimension hollow sandwich composites (3D composites) with pile height of 5, 6 and 7 mmwere selected as object of study. In order to study low-velocity impact properties of the 3D composites, low-velocityimpact testing was conducted by using drop hammer low-velocity impact tester at energy of 8 J. In addition, compressivestrength of the 3D composites before and after impacting was tested by using universal material testing machine(Instron 3385H) for studying compressive damage tolerance of the 3D composites suffering low-velocity impact loads.The results indicate that the 3D composites were sensitive to low-velocity impact loads. Low-velocity impact propertiesincreased with the increase of pile height of the 3D composites. Residual compressive strength of the 3D compositesdeclined sharply after suffering low-velocity impact loads. The results contribute to the optimal design of the 3D sandwichcomposites. >工程实践
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2014, 44(6).
Abstract:
A machining method of the large diameter and non-orthogonal intersecting lines of holes of carbon fibercomposite materials is introduced in this paper. The problem of process temperature, machining quality, chip removingand processing efficiency are considered. The size and position accuracy of the hole are guaranteed by an easymechanical devices, which make the intersecting lines of holes can be produced in one operation. The problem of chipremoving and heat dispassion is solved by the improvement of the traditional diamond grain, and the quality of the machinedsurface of the composites is greatly improved. -
2014, 44(6).
Abstract:
In this work, the pulling test condition and test results of M5 post-insert through-hole connector in ahoneycomb panel were discussed. The influence of post-insert connector application and curing processing protocol onthe pulling strength and bonding quality were analyzed. It was found that the best way to apply the resin is to installthe inserts after vertically fill the resin along the axial of the through holes. Minimum pores and improved pullingstrength were achieved with this method. For EA934NA post-insert bonding agent, curing at room temperature ( ≥22℃) is preferable for better pulling strength. The conclusions of this work can be used as references for future producttest design and processing configuration setup. >科技信息
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2014, 44(6).
Abstract:
A new forming process,the hybrid forming of aluminum alloys is introduced in this paper. This formingprocess has been applied in high-class vehicles. In this process, the aluminum alloy sheet is formed and quenched simultaneouslyfollowed by a second stage precipitation period. By using this forming process, the formability and strengthof aluminum alloys has greatly improved. A much lighter and stronger component, with more complex geometry can beobtained. The potential application of hybrid formed aluminum alloys components in aircrafts is discussed. This paperprovides references for forming and processing of aluminum alloys, as well as the industrialization of HFQ in China. -
2014, 44(6).
Abstract:
In this paper, we simply introduced some applications of the matte paint at domestic and abroad, andexpounded the measuring method of extinction performance index, and then compared the values of their extinctionperformance.
