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Using scientific evaluation methods to evaluate the mission effectiveness and cost-efficiency of rockets is one of the important topics in the development of rocket models. Aiming at the problem that the effectiveness evaluation of carrier rockets cannot be quantitatively analyzed, this paper takes the medium-sized carrier rockets, covering both new and old generation ones in service, as the object of establishing a simplified inherent capability index system. The ADC method is utilized to quantitatively evaluate the availabilities, dependabilities, and capabilities of various types of rockets and calculates the corresponding effectiveness and cost efficiencies when performing launch missions in LEO, GTO, and SSO orbits. The results show that Model II has excellent mission effectiveness, which is particularly suitable for medium and high orbit missions; the cost-efficiency of Model III is as good as that of the former, and it can complete many tasks; but Model I is outdated.

Vertically aligned nanographite structures, the so-called carbon nanowalls (CNWs), are decorated with ultrananocrystalline diamond particles by an electrostatic self-assembly seeding technique, followed by short-term growth in plasma chemical vapor deposition, to enhance field emission efficiency and stability. A nanodiamond suspension diluted with a dispersion medium with high wettability on CNWs enables seeding of diamond nanograins consisting of nanoparticles of 3-5 nm in diameter on CNWs with high uniformity and minimal aggregation and control of their number density. The field emission turn-on field depends upon the density of diamond nanograins and decreases from 3.0 V μm

ZrO2/yttria-stabilized zirconia (YSZ) doping Al2O3 ceramic coating was fabricated via cathodic plasma electrolytic deposition (CPED) technique. The microstructures and the chemical and phase compositions of the doped coating were characterized, the mechanical properties and the high temperature oxidation resistance were evaluated, and the doping mechanism was also discussed in detail. The results showed that, doped Zr4+ and Y3+ ions could effectively reduce the working voltage during CPED process and increase the content of metastable γ-Al2O3 in the coating. Accordingly, the doped ZrO2/YSZ significantly refined the grain size of Al2O3, as well as remarkably improved the high temperature oxidation resistance, the micro-structural compactness and hardness of the Al2O3 CPED coating. This study displayed here constructed an efficiently method for the fabrication of multifunctional coating on the surface of TiAl alloy.

CeO2 doped Al2O3 composite ceramic coatings were fabricated on TiAl alloys via cathodic plasma electrolytic deposition technique in 0.3 mol/L Al(NO3)3 ethanol electrolytes containing different concentrations of Ce(NO3)4. The effects of CeO2 doping contents on microstructures, elemental compositions, mechanical properties, high temperature oxidation resistance at 850 °C, and wear resistance against GCr15 balls at 200 °C of the coatings were investigated. The results indicated that the contents of CeO2 in composite coatings increased with increasing concentration of Ce(NO3)4, and composite coatings were composed of α–Al2O3 mainly, γ–Al2O3, and a little CeO2. The doping of CeO2 helped to improve the phase inversion from γ–Al2O3 to α–Al2O3. The crystallization and wear resistance of composite coatings increased due to the doping of CeO2. In the electrolyte containing 0.015 mol/L Ce(NO3)4, the coating was the most uniform and compact, and of the best high temperature oxidation resistance and mechanical properties.

The knowledge of process parameters–weld integrity-aging treatments–tensile property relationship is of great concern for linear friction welded (LFWed) Ti2AlNb-based alloy and requires a systematic characterization. Thus, the Ti2AlNb-based alloy was LFWed under various process parameters and then subjected to different aging treatments. Twelve welding conditions were used to evaluate the weld integrity, showing that impurities and cracks at weld interface can be eliminated under strong welding parameters and the feed rate has the greatest influence on the weld integrity among all process parameters. Relationships among aging temperatures, microstructure evolution, and mechanical properties were investigated. After aging treatment, acicular O phase has precipitated in B2 grains both in the weld zone and thermo-mechanical affected zone (TMAZ). The size of precipitated O phase increases along with the increase of temperature, and the α2 + O mixtures have finally decomposed into the aggregated acicular O phase. The microhardness and tensile strength of the joints have been enhanced due to the precipitation hardening of O phase and refined grain strengthening after aging treatments.

In order to increase the surface hardness and wear-resistance property of sled track slippers, a Ni80Al20-MoS2 composite coating was fabricated on the surface of a stainless steel 0Cr18Ni9Ti sled track slipper via atmospheric spray and hot dipping. The microstructure, composition and surface hardness of coatings under different spraying powers were characterized and measured. The wear-resistant properties of the slipper substrate and the coating were also checked. The results showed that the higher the spraying power was, the greater the smoothness, density and hardness was of the Ni80Al20 coating, while the thickness initially increased and then decreased. When the spraying power was 18 kW, the thickness was 342.5 &mu, m, the surface hardness was 304.1 Hv0.2, and the coating was composed of Ni, Al, Ni3Al, NiAl and a little Al2O3. The friction coefficient of the slipper substrate against GCr15 balls at room temperature in air was 0.7, while the coated substrate with MoS2 lubrication film was 0.3 and the volume wear rate declined by 1/5. The friction coefficient of the Ni80Al20 coating was 0.5 and the Ni80Al20-MoS2 composite coating was 0.15, while the volume wear rate declined by 1/4 and 1/3.

The effects of ZrO2 nanoparticles in a NaAlO2 electrolyte on the thickness, morphology, composition, structure, and high temperature oxidation resistance of plasma electrolytic oxidation (PEO) coatings on a TC21 titanium alloy were investigated. The coating thickness increased with increasing concentration of ZrO2 nanoparticles in the electrolyte, accompanied by a decrease in the porosity of the coating surface. The PEO coatings formed in the ZrO2 nanoparticle-free electrolyte were composed of Al2TiO5. ZrTiO4, m-ZrO2, and t-ZrO2 were detected in the PEO coatings produced by the electrolyte that contained ZrO2 nanoparticles, which indicated that the deposition mechanism of the nanoparticles was partly reactive incorporation. The high temperature oxidation resistance of the TC21 titanium alloy at 650 &deg, C and 750 &deg, C was improved by 3&ndash, 5 times after PEO treatment. The oxidation mechanism involved oxygen diffusing inward to form an oxide layer at the interface of the PEO coating and substrate.

Seeding of diamond nanoparticles on vertically-aligned multi-layer graphene, the so-called carbon nanowalls (CNWs), is studied by using deionized water, ethylene glycol, ethanol, and formamide as dispersion mediums. Detonation nanodiamond particles show the smallest mean size and size distribution with a high positive zeta potential when dispersed in ethanol. The contact angle of ethanol on CNWs is almost zero degree, confirming highly wetting behaviour. The diamond nanoparticles dispersed in ethanol are distributed the most uniformly with minimal aggregation on CNWs as opposed to those dispersed in other liquids. The resulting diamond nanoparticle-seeded CNWs, followed by short-term growth in microwave plasma chemical vapor deposition, show a marked decrease in field emission turn-on field down to 1.3 V μm−1 together with a large increase in current density, compared to bare CNWs without diamond seeding. The results provide a way to control the density, size, and uniformity (spacing) of diamond nanoparticles on CNWs and should be applied to fabricate hybrid materials and devices using nanodiamond and nanocarbons.

Barrier layer was prepared on TiAl alloy by Micro-arc oxidation(MAO) technique in silicate electrolyte, and cathodic plasma electrolytic deposition (CPED) technique was used to fabricate Al2O3 ceramic coating on prepared TiAl alloy in Al(NO3)3 (30 g/L) ethanol electrolytes with different water content by volume. Microstructure, composition and properties of coatings were analyzed, and mechanisms of different electrolytes were evaluated. The results showed that both arc-voltage and work voltage decreased with the increase of water content. Al2O3 CPED coatings were composed of deposition particles and cracks, and contained α-Al2O3 phase mainly and a small amount of γ-Al2O3 phase. The organic reaction mechanism was studied and the performance of TiAl alloy with CPED coating under 950 °C was superior to TiAl substrate.

Basic and ZrO2 doped composite plasma electrolytic oxidation coatings were prepared on the surface of TC21 titanium alloy. Subsequently, fretting wear tests of these two kinds of coated samples and the substrate alloy against GCr15 steel balls were conducted at 50 μm and 150 μm displacement amplitudes. The morphology, composition, valence states and topography of the fretting wear tracks were characterized and the wear mechanisms were studied. The results indicated that the porosity of the composite coatings was lower than that of the basic coatings, and the microhardness, adhesion strength and toughness were higher. When the fretting was in the partial slip regime (50 μm displacement amplitude), the fretting damage of the three materials was slight. Meanwhile, the cracks and delamination in the microslip zone of the TC21 alloy were not observed in the coated samples. When the fretting was in the slip regime (150 μm displacement amplitude), although the TC21 alloy and basic coatings experienced local wear, there was no significant material loss of the composite coatings, which demonstrated that the composite coatings could improve the fretting wear resistance.

In order to improve the oxidation resistance of TiAl alloy, silicide coatings were prepared by pack cementation method at 1273, 1323, and 1373K for 1-3 hours. Scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD) were employed to investigate the microstructures and phase constitutions of the coatings. The experimental results show that all silicon deposition coatings have multi-layer structure. The microstructure and composition of silicide coatings strongly depend on siliconizing temperatures. In order to investigate the rate controlling step of pack siliconizing on TiAl alloy, coating growth kinetics was analyzed by measuring the mass gains per unit area of silicided samples as a function of time and temperature. The results showed that the rate controlling step was gas-phase diffusion step and the growth rate constant (k) ranged from 1.53 mg2/(cm4·h2) to 2.3 mg2/(cm4·h2). Activation energy (Q) for the process was calculated as 109 kJ/mol, determined by Arrhenius' equation: k = k 0 exp[–Q/(RT)].

Oxidation behavior of a Ti2AlNb based alloy (Ti–22Al–23Nb (at.%)) and hot corrosion behavior of this alloy coated with a salt mixture of NaCl–Na2SO4 at 1023 K were comparatively investigated. The results showed that the alloy possessed relatively good oxidation resistance while suffered severe hot corrosion attack. The mass gain of the hot-corroded alloy was much larger than that of the oxidized alloy. The oxide scale was mainly composed of TiO2. During the oxidation, the oxide scale could keep intact. In the corrosion product scale, TiO2 + Al2O3 layers and NaNbO3 layers existed alternately and Al2O3 was distributed in the lower parts of the TiO2 + Al2O3 layers. The formation of the TiO2 + Al2O3 layer and the NaNbO3 layer should promote each other by altering the acidity/basicity of the salt film, and thus the growth of the scale was accelerated. The escape of the gaseous chlorides, the fast growth of the scale and the coefficient of thermal expansion (CTE) mismatch between TiO2 and NaNbO3 resulted in serious cracking and spalling of the scale.

To improve the fretting wear resistance of TC6 alloy, AT40 coating and Al2O3/AT40 composite coating were prepared on TC6 respectively by atmospheric plasma spraying (APS) technology. The microstructure, composition and adhesion strength of the two coatings were studied, and the fretting wear behavior of TC6 substrate and the coatings were investigated. The results showed that the two coatings were of lamellar stacked structures with holes and micro-cracks in stacked areas, and combined well with substrate. AT40 coating was composed of the Al2TiO5, Ti3O5 and α-Al2O3, and Al2O3/AT40 composite coating was formed by inner transition AT40 layer and outer Al2O3 layer. The inner transition AT40 layer had good compatibility with TC6 titanium alloy and Al2O3 layer, and the outer Al2O3 layer consists of α-Al2O3 and γ-Al2O3. The two coatings significantly improved the fretting wear resistance of TC6 alloy, and the fretting wear mechanism of the two coatings was fatigue wear and slight adhesive wear.

Al2O3 coating was fabricated on the surface of γ-TiAl alloy via cathodic plasma electrolytic deposition (CPED) technique. The microstructure and the composition of the coating were elaborately characterized. The results revealed that, the uniform coating combined well with the substrate, which was mainly composed of α-Al2O3, γ-Al2O3 and trace amount of amorphous Al(OH)3. Moreover, the high temperature oxidation behaviors of the substrate, the coating and their interface were investigated in detail. It was found that the existence of the Al2O3 coating could substantially decline the oxidation rate of TiAl alloy, because of the significant increase in high temperature oxidation resistance.

Coatings were prepared by aluminization of a Si–Y co-deposition coating on a Ti2AlNb based alloy using halide activated pack cementation technique. The microstructure evolution and the high temperature oxidation behavior of the coatings were investigated. During the aluminization, the (Ti,Nb)5Si4 inner layer of the Si–Y co-deposition coating was consumed faster than the (Nb,Ti)Si2 outer layer. A (Ti,Nb)Al3 superficial layer and a (Nb,Ti)3Si5Al2 + (Ti,Nb)Al3 middle layer successively formed. Besides, (Nb,Ti)3Si5Al2 pieces appeared inside the outer layer when solid solution Al in (Nb,Ti)Si2 reached saturation. Both inward diffusion of active [Al] atoms and outward diffusion of Ti and Nb atoms controlled the coating growth. The outward diffusion of Ti and Nb atoms caused Al beneath the inner layer was enriched continuously. The Si–Y co-deposition + aluminization coating could provide better protection for the Ti2AlNb based alloy from oxidation at 1123 K than the Si–Y co-deposition coating, which was attributed to preferential formation of Al2O3 on the surface to prohibit formation of loose TiO2. After the oxidation for 100 h, a continuous, compact and adhesive oxide scale consisting of an Al2O3 main part and an Al2O3 + TiO2 + SiO2 lower part formed on the coating.

The protective chromium coating was prepared on P110 steel by employing pack cementation. The corrosion behaviors of P110 steel and the obtained coating in CO2-saturated simulated oilfield brine were studied by static complete immersion tests and electrochemical measurements. The corrosion attacks of the samples were determined by mass loss, corroded surface morphologies, corrosion products, and results of electrochemical measurements. The experimental results showed that the coating was uniform, continuous and compact. The chromium coating was slightly corroded, and the mass loss and corrosion rate of the coating were far lower than those of P110 steel. Chromium coating has higher self-corroding potential and lower corrosion current density than P110 steel in accordance with the electrochemical tests results. Taken as a whole, chromizing treatment has significantly improved the corrosion resistance of P110 steel.

In order to obtain a high-performance surface on P110 steel that can meet the requirements in oil/gas field environment, the chromium coatings were fabricated by pack cementation. The chromium coatings differed in with/without the addition of La2O3. Scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS), X-ray diffractometer (XRD) and microhardness tester were employed to investigate the surface morphologies, surface element distributions, microstructures, phase constitutions and microhardness of the coatings. Friction-wear tests of the P110 steel substrate and the coatings were conducted in air at ambient temperature and humidity. The results show that uniform and continuous coatings are formed on P110 steel regardless of adding La2O3 or not. The chromium coatings consist of Cr23C6, Cr7C3, and (Cr, Fe)7C3. The La2O3-added chromium coating is more beneficial in terms of surface morphology, microstructure, thickness and microhardness as compared with the coating without adding La2O3. Chromizing treatment significantly improves the surface hardness and wear resistance of the P110 steel. The wear resistance of the tested samples can be sorted in the following sequence: La2O3-coating>no RE-coating>bare P110 steel.

Mosquitoes are a type of amphibian insects with remarkable ability to walk freely, lay eggs and safely take off or land on the water surface without drowning. This article reports the water repellency mechanism of mosquito legs. The maximal supporting force of a single hind leg against water surprisingly reaches up to 600 μN, over twenty times the total body weight of this insect. While for the artificial leg made with the wire which has the same diameter, shape and structure to the mosquito leg, the supporting force is only 85 μN, far less than the value of mosquito leg. Scanning electron microscope (SEM) observations reveal the uniquely hierarchical micro-nano structure on the legs, consisting of numerous oriented ten-micro scales with uniform sub-micro longitudinal ridges and nanometer cross ribs. The surface of mosquito leg has superior water repellency, and its static contact angle is about 153°. We theoretically demonstrate that the hierarchical micro-nano structure on the surface of the mosquito leg renders such superior water repellency and high water-supporting force. This finding might be helpful in the design of innovative non-wetting materials.

In order to improve the corrosion resistance and increase the service lifetime of P110 steel during operation, four chromizing coatings were formed onto its surface with/without addition of rare earths via pack cementation process. The surface morphologies and microstructures of the chromizing coatings were observed using scanning electron microscopy (SEM), and the phase constitutions were investigated by X-ray diffraction (XRD). Electrochemical corrosion behavior of the chromizing coatings in simulated oilfield brine at 30 °C was studied by means of open-circuit potential measurements and cyclic potential dynamic polarization tests. The results showed that the coatings were mainly composed of Cr 23 C 6 , Cr 7 C 3 , and (Cr, Fe) 7 C 3 . There were obvious differences in surface morphologies and microstructures of the coatings. The thickness values of the coatings were arranged as follows: CeO 2 >-coating>Y 2 O 3 -coating>La 2 O 3 -coating>no RE-coating. The corrosion resistance of the coatings was sorted in the following sequence: CeO 2 2 O 3 -coating 2 3 -coating. Adding various rare earths could influence the microstructures and corrosion resistance of the chromizing coatings indeed.

To evaluate the results of the reconstruction of the soft tissue defects following the en block resection of tongue cancer using free anterolateral thigh myocutaneous flaps.From November 2006 to December 2008, 109 cases underwent the reconstruction of the soft tissue defects following the en block resection of tongue cancer using free anterolateral thigh myocutaneous flaps. There were 75 males and 34 females with an age of 23-75 years (50.4 years on average). The disease course was 1-6 months. According to 2002 International Union Control Cancer (IUCC) criterion for TNM stage, there were 35 cases of T2N0M0, 8 cases of T2N1M0, 2 cases of T2N2M0, 31 cases of T3N0M0, 12 cases of T3N1M0, 7 cases of T3N2M0, 5 cases of T4N0M0, 4 cases of T4N1M0, 3 cases of T4N2M0, and 2 cases of T4N3M0. The range of tongue defect was 5 cm x 3 cm to 12 cm x 8 cm. The flap area ranged from 7 cm x 4 cm to 20 cm x 8 cm. Eighty-two patients with T3, T4 and positive lymph node metastasis determined by pathological examination after operation received radiotherapy. The vitality of the flaps and the healing of the wounds were observed postoperatively. The shape and function of the reconstructed tongue were determined, the influences on function at donor site were evaluated and the flap tolerance to radiotherapy was investigated during the follow-up period.Mouth floor mandibular fistula occurred in 5 cases 5-7 days after operation, seroma formation in 1 case and wound dehiscence in another case at the donor site; the wounds healed by secondary intention after dressing. The other wounds healed primarily. All 105 flaps survived completely, 3 flaps developed partial necrosis 3-5 days after operation, the wounds healed after dressing; and 1 flap failed 3 days after operation, then it was removed and defects was repaired using pectoralis major muscle flap. Blisters occurred in 8 flaps (all being thinning flaps) 1 day after operation. The overall complete survival of the flap was 96.3% (105/109). The patients were followed up for 0.5-2.5 years (1.2 years on average). Although the flaps had a little atrophy, the shape of the reconstructed tongue was still satisfactory with suitable tongue-mandibular groove. No depression was observed in the mandibular region. The speech as well as swallowing function were well recovered. The scar was easily hidden with no important functional impairment at the donor site. No flap necrosis occurred in all the patients who received postoperative radiotherapy.Free anterolateral thigh myocutaneous flap transplantation is safe and reliable, and it has the advantages of the better result at the recipient site, the less morbidity at the donor site, fewer postoperative complications and excellent tolerance to radiotherapy. So it is an ideal flap to repair soft tissue defects following the en block resection of tongue cancer.