Background: Titanium (Ti) and its alloys are potential metal materials in dental and orthopedic applications, due to their excellent mechanical properties and biocompatibility. Despite these properties, revision surgery is painful for millions of patients and may cause secondary injury, calling for a solution to this issue. Compared to antibiotics used in a clinical context, novel biomaterials display powerful application potential due to their stronger antibacterial activity, reduced drug resistance and excellent biocompatibility. Antibacterial ions have a crucial effect, particularly for nanostructured metals. Objective: This review focuses on the antibacterial functions and osteogenic properties of surface modification based on Ag, Zn, Cu and other nonmetallic ions. Methods: The first part of the review briefly describes the issues with bacterial infection of Ti implants. The methods of surface modification are then introduced in detail. Lastly, other strategies used to improve antibacterial and osteogenic properties are also provided. Conclusion: Although anti-infective research is valuable, there is still a gap present between theoretical strategies and those that are clinically implemented strategies. There is an urgent need to transform the findings of research into clinical applications.

本文模拟建立了潜艇均衡系统自流注水试验系统,对不同假海压力、不同系统流量、不同出口背压及串联2台调节阀时自流注水稳定过程振动噪声进行研究.结果 表明:潜艇均衡注水振动噪声随着假海深度的增大而增大;空气噪声随流量调节阀开度的增大而增大,在流量调节阀开度为60°～ 70°之间,振动加速度及水动力噪声产生峰值;在出口背压为0～0.5 MPa之间时,振动噪声值均大于无背压状态,峰值为0.2 MPa;串联2台流量调节阀可大幅降低自流注水振动噪声.

Although Ti-6Al-4V has been widely used in biomaterial field. Compared with other classes of materials, it still encounters some problems such as low surface hardness and relative low biocompatibility. To solve these problems friction stir processing (FSP) was applied to fabricate a nanosized composite layer of TiO2 and Ti-6Al-4V. Uniform distribution of TiO2 particles with some clusters on the surface of alloy can be observed. Due to severe plastic deformation and stirring heat, nanocrystallines and amorphous TiO2 can be observed in stir zone. FSPed samples show significant improvement in surface microhardness and biocompatibility due to its modified structure compared with original sample. In addition, through corrosion behaviors of the samples in simulated body fluid, it is found that FSP can enhance whilst TiO2 reduces the possibility and corrosion rate of material in environment of human body. (C) 2017 Elsevier B.V. All rights reserved.

TiC-reinforced Ti matrix composites of various TiC volume fractions were prepared via an in situ synthesis method. The microstructure of the composites was refined by thermo-mechanical processing yielding Widmanstätten and bimodal microstructures. The strengthening effects exerted by TiC reinforcement and microstructure refinement in the composite were evaluated via tensile tests at 873K, and the strengthening mechanisms were investigated by transmission electron microscopy and mechanical models. The addition of carbon increased the beta transfus temperature of the composite significantly. The strengthening effect exerted by the solid solution carbon and dislocation hindering by the TiC particles played important roles in determining the strength of the prepared composites. In composites that featured Widmanstätten and bimodal microstructures with no precipitated silicides, the size of the α colonies was an important factor that determined the composite strength. In contrast, in composites wherein silicide precipitation had occur, the size of the α plates was a contributing factor owing to the dislocation hindering effect exerted by the silicides.

: Friction stir processed (FSPed) NAB alloy exhibits inhomogeneous microstructures that can be divided into three subregions from the top surface to the bottom according to α phase morphologies: Widmanstatten α subregion, banded α colonies, and stream-like α colonies. In this study, a constant stress intensity range (Δ K ) was used for each sample to study the effect of microstructures on the fatigue crack growth rate (FCGR) of FSPed NAB alloy. The results show that α phase in banded and stream-like α colonies experiences completely dynamic recrystallization and forms equiaxed α grains during FSP. The FCGR of FSPed NAB alloy continuously decreases from the top surface to the bottom. In the subregion with stream-like α colonies, the alloy containing a higher content of equiaxed α grains and fine κ iv phase, and less retained β ( β ′) phase exhibits the best FCG resistance. The equiaxed α grains deflect the main crack and increase crack tortuosity effect, which make a main contribution to FCG resistance of FSPed NAB alloy, while martensite β ′ phase produced during FSP accelerates its fatigue crack growth. Compared to matrix alloy, FSPed NAB alloy exhibits better FCG resistance only at high Δ K levels. At low Δ K levels, the crack deflection effect caused by coarser κ phase in the matrix alloy obviously improves its FCG resistance. With the increasing Δ K , the aforementioned crack deflection effect gradually diminishes and fatigue crack prefers to propagate in a flat way, resulting in higher FCGR of matrix alloy.

Friction stir processing was utilized to prepare silver-loaded layer on the surface of Ti-6Al-4V (TC4) titanium alloy successfully.The morphology, distribution and influence on the mechanical properties of silver in the silver-loaded layer were studied.The results show that a silver-loaded layer of 700 μm in thickness was successfully fabricated.A large number of silver nanocrystallines with 10 nm in average diameter were observed in the top surface of silver-loaded layer due to mechanical nanocrystallization resulted from strong stirring shear force.In the sub-surface of silver-loaded layer, silver particles precipitated and formed a solid bonding with the matrix and free particles would barely appear in service.Uniformly distributed silver particles made the surface nanohardness of the silver-loaded layer about 30% higher than that of the silver-free zone, while it had little effect on the elastic modulus of the matrix.

The simulation experiment system of warship trim balance moving water was established in this paper.The transient noise in the process of moving water is studied under different of pressure of moving water,the opening and closing time of the electro-hydraulic ball valve and the fixed mode of the pipeline.The results show that the transient noise value in the process of moving water is in a curve wave state.The maximum vibration acceleration and the maximum value of air noise are all occurred in the course of electro-hydraulic ball valve closing.With the increase of pressure of moving water,the maximum noise is gradually increased.When the electro-hydraulic ball valve is closed quickly,there is a clear water hammer in the water transfer pipeline.Prolonging the closing time of the electro-hydraulic ball valve can effectively restrain the impact of water hammer and reduce the maximum noise.The elastic support method can effectively reduce the vibration noise in the process of moving water.

Arming at the low corrosion resisting and low service life for ball valve of ship,a new type of ball valve made titanium for ship is designed and developed. The valve is good in sealing performance,seawater corrosion resisting,and service life. The structure design,sealed structure design,and choice of material for ball valve are introduced in the paper.

Three-pass friction stir processing (FSP)was carried out on pure titanium plates at different rotation speeds,microstructure,hardness and friction and wear properties of friction stir processed zone were studied,and wear morphology and mechanical of the titanium plates before and after FSP were analyzed.The results show that stir zone exhibited severe plastic deformation,this resulted in a uniform recrystallized microstructure. With the increase of rotation speed,grains of stir zone were further refined.The highest hardness of 430 HV was obtained in friction stir processed zone,improved by 87% compared to 230 HV of the substrate.Average friction coefficient and wear rate of friction stir processed sample were 0.24 and 5.36×10-4 mm3.N-1.m-1 .Wear mechanism of the substrate was adhesive wear,and that of friction-stir processed sample mainly was abrasive wear.

The invention discloses a two-way displacement type proportional electromagnet, belongs to electromagnets, and solves the problems that the whole performance is not easy to improve and the cost is increased by adopting two one-way output type electromagnets in the conventional proportional valve. The two-way displacement type proportional electromagnet comprises a shell, a framework, an armature, a left coil, a right coil, a left end cover, a right end cover, a left reed and a right reed. The two-way displacement type proportional electromagnet adopts an integral structure, is easy to assemble and debug and realizes two-way displacement output, the processing cost is reduced, the two-way displacement type proportional electromagnet can be directly connected with a valve element of a slide valve, the proportional control of the position of the valve element of the slide valve is realized, and the slide valve outputs flow proportional to a control signal, so that the proportional valve is convenient to use and excellent in performance, and zero adjustment is more simple and convenient.

The single hot compression tests of SPHC steel were performed using a Gleeble-1500 thermome-chanical simulator. The characteristics of strain induced transformation and ferrite grain refinement were investigated through analyzing the stress-strain curves and metallographic structures. The results show that very fine ferrite grains of about 1.6～4.6μm can be obtained by the deformation at 750～830 ℃,due to the occurrence of SIFT. Decreasing deformation temperature leads to increase the chemical driving force for austenite-to-ferrite transformation and thus leads to refine ferrite grain. The size and volume fraction of ferrite grains decrease with increasing strain rate at the same strain level.

The static softening behavior of aluminum alloy A6082 was investigated by interrupted hot tests conducted on Gleeble-1500 simulator at deformation temperatures from 573 to 773 K and strain rates from 0.1 to 10 s −1 , with a pre-strain from 0.3 to 0.7 and variable inter-pass delay times. The offset method was applied to convert the changes in flow stress between two passes to static softening fraction. The microstructural changes were characterized by the quantitative metallography of quenched specimens. The results showed both static softening and static recrystallization curves exhibited a simple sigmoidal shape; the static softening is related to the static recrystallization in a nonlinear manner with 50% static recrystallized volume fraction corresponding to 80% static softening fraction; an increase in temperature, strain rate or pre-strain yields a decrease in the time for 50% static recrysallized volume fraction, on which the temperature has the most remarkable influence; Si and Mn additions accelerate the process of static recrystallization. Finally, the equations of static recrystallization kinetics of this alloy were developed with a good agreement between the predicted and experimental results.

The flow stress behavior of aluminum alloy 6A10 was studied by the hot compression tests at temperatures from 350 °C to 550 °C and strain rates from 0.1 s−1 to 10 s−1 with Gleeble-1500 thermo-mechanical simulator. The result demonstrates that the temperatures of specimen differ from initial ones affected by deformation conditions, and that the softening mechanism is dynamic recovery. A new approach was proposed to analyze the flow stress character directly from actual stress, strain, temperature and strain rate data, without performing any previous flow stress correction caused by temperature variation. Comparisons between the experimental and predicted results confirm that the established flow stress model can give reasonable estimation, indicating that the mentioned approach can be used in flow stress model analysis of the materials that undergo only dynamic recovery based on the data obtained under variable deformation temperature.

The dynamic recrystallization (DRX) behaviors in SPHC steel were investigated with hot compression tests at deformation temperatures of 950–1 150 °C, strain rates of 0.1–15 s−1, and initial austenite grain sizes of 86–232 μm. The effects of deformation temperature, strain, strain rate and the initial austenite grain size on the microstructural evolution during DRX were studied in detail. The results show that DRX is observed under the condition of the Zener-Hollomon parameter being less than 1.07×1013 s−1. The deformation activation energy for SPHC steel is calculated to be 299.4 kJ/mol by regression analysis. Austenite grain size of DRX is refined with decreasing temperature and increasing strain rate under steady state conditions, but it is not influenced by the initial grain size. The mathematical equation of DRX grain size of SPHC steel is obtained.

The hot compression tests on an SPHC steel were carried out in the temperature range of 900 — 1150 °C and strain rate range of 0.1 —10 s−1, in which the maximum true strain is 0.8. The activation energy of test steel was calculated, to be 299. 4 kJ/mol. The critical stresses and strains for initiation of dynamic recrystallization were determined based on changes of the work hardening rate (θ) as a function of the flow stress (σ) or strain (ɛ), respectively. The dependence of the peak strain (ɛp), the peak stress (σp), and the steady state stress (σs) were determined based on the Zener-Hollomen parameter. The mathematical models of the flow stress evolution were established in the hardening and dynamic recovery region and dynamic recrystallization region, respectively. The average error between experimental curves and predicted ones was around 3.26%.

A new processing method,equal channel angular pressing（ECAP）plus cold rolling（CR）,was applied to producing ultra-fine grained FeCoV alloy.The microstructures of ultra-fine grained FeCoV alloy after ECAP,ECAP plus CR,and the effect of tempering treatment on the microstructure of FeCoV alloy produced by ECAP plus CR were investigated.The results show that an elongated substructure with a width of about 0.3μm is obtained after four-pass ECAP using Route A.Cold rolling after ECAP cannot change the morphologies of elongated substructure,and it results in higher fraction of high-angle boundaries and higher dislocation density compared with the identical ECAP without rolling.Subsequent tempering for 30 min at 853 K brings about many nano-phases precipitating at subgrain boundaries and insides the grains,and the size of precipitated phase is measured to be about 10 nm.Nano-phases grow up with increasing tempering temperature and equiaxed structure forms at 883 K.

The magnetic properties of 2J4 alloy deformed by the equal channel angular pressing(ECAP) have been studied in different tempering temperature,and were contrasted with those of the cold rolling 2J4 alloy.The results shows that the more the ECAP deformation extent is,the better the magnetic permeability of 2J4 alloy will be,the relation between them is the positive pertinence.The saturation magnetic flux density of 2J4 alloy is the best after four passes ECAP.Moreover,the change of the magnetic performance of 2J4 alloy is very sensitive to the change of tempering temperature.The best magnetic retardation performances are found in the 2J4 alloy,which is rolled with a deformation amount of 85%,along the extruding direction after four passes ECAP deformation.Its coercive force reaches 3.8364 kA/m.The magnetic retardation performance of ECAP 2J4 alloy is better than that of traditional cold rolling 2J4 alloy.The results favors that the fabrication of high performance magnetic material by means of ECAP is feasible.

Dynamic recrystallization(DRX) and austenite grain size after recrystallization under different deformation conditions for 40Cr steel were studied on a Gleeble-1500 thermomechanical test system.The austenite grain size of 9 μm can be produced by dynamic recrystallization by optimizing processing condition of deformation temperature,reduction and strain rate.The final dynamically recrystallized austenite grain size depends on Zener-Hollomon parameter,which is increased with increasing strain rate and decreasing deformation temperature.The mathematical equation of DRX grain size of 40Cr steel was obtained.

The influence of Equal Channel Angular Pressing(ECAP) deformation on the microstructure and magnetic properties of a semi-magnetic alloy,2J4,was studied.In the process,the sample is pressed from one pass to the next pass directly without rotation.Results show that the microstructures of 2J4 alloy deformed by ECAP at room temperature are obviously refined.Part of original austenite transforms into martensite,the larger the deformation,the higher the transformation fraction of martensite.The magnetic retardation performance of the specimen deformed by ECAP is better than that deformed by cold rolling with similar deformation.It has higher coercive force(Hc),remanence(Br) and larger magnetic energy(Pro).ECAP deformation is new approach for fabricating high performance magnetic materials with high material utilization and low production cost.