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Pulsed laser deposition (PLD) is being investigated as an alternative technique to prepare hydroxyapatite coatings. In this research we studied the microstructure and phase composition of the PLD hydroxyapatite films. The surface morphology of the films is composed of droplets for which size ranges from hundreds of nanometers to a few micrometers. The cross-sectional morphology of the films shows that the films adhere to the substrate well and there are no microcracks, pores and other defects between substrate and films. The X-ray diffractometer results show that the deposited films are amorphous and the post heat treatment films consists of crystalline HA and TiO 2.

This study was aimed at the pulsed laser deposition of hydroxyapatite (HA) thin films onto Ti substrate using KrF excimer laser. The deposition was carried out under an atmosphere of Ar at 45 Pa. The films structures have been analyzed by EPMA, TEM, XRD and Raman spectroscopy. It can be observed that the films are mainly composed of droplet-like particles which size of 0.2–2 μm. The results of XRD, TEM and Raman spectroscopy show that the films are amorphous. The ratio of Ca/P is 1.97, which is higher than that of HA. After heat treatment the XRD pattern show that the films were consist of HA and TiO 2 . The ratio of Ca/P is 1.82, which is close to that of crystalline HA.

A ceramic like coating was deposited on the substrate of pure magnesium by microarc oxidation. X-ray diffraction, scanning electron microscopy and energy dispersive spectrometry were used to analyse the structure and composition of the coating. X-ray diffraction showed that the phases present in the coating were mainly MgO with some Mg(OH)2. Energy dispersive spectrometry indicated that silicon could be absorbed into the coating in the microarc oxidation process. Scanning electron microscopy showed that the coating surface possessed a porous microstructure, and the pore size was in the range of 1–3 μm. The coating matrix was relatively dense and had a homogeneous thickness. The hardness of the MgO coating could reach 530 HV(0·025 g) and was ∼10 times higher than that of the substrate.

In this paper, the influence of different laser power and scanning speed on the microstructure of laser remelted as-sprayed hydroxyapatite (HA) coatings was studied and the optimum technological parameters were obtained. The morphologies, elements and phase analysis of both sprayed and remelted coatings were examined by means of electron probe microanalysis, x-ray diffraction and so on. The results show that the plasma sprayed coatings could be improved by laser remelting and the optimum technological parameters are that the laser power is 600 W and the scanning speed is 11.2 mm s−1. In the technological condition, the remelted coating which has compact columnar and cellular dendritic crystal consists of HA, α-TCP, CaO and TiO2 phases, and the Ca/P ratio of the coating is the most approximate to that of HA. When increasing the laser power and slowing the scanning speed, the structure of the coating will become much coarser and the Ca/P ratio will deviate more from that of HA. On the contrary, if the laser power is reduced and the scanning speed is accelerated, the influence of technological parameters of laser remelting on the sprayed coating will be weakened.

Ceramic-like coatings were deposited on the substrate of the AZ91 alloy by micro-arc oxidation (MAO). Many methods like X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron diffraction spectroscopy (EDS) were used to analyze the structure and composition of the coating. XRD showed that the MAO coating was mainly composed of MgO . The results of SEM showed that the coating surface possessed a porous microstructure and the pore size was in the range of 1–3 μm. EDS indicated that the coating matrix was relatively dense and had a homogeneous thickness. The element silicon from the applied electrolyte could be absorbed into the coating in the MAO process. The hardness of the MgO coatings could reach 513 HV0.025that was about four times higher than that of the substrate. It is expected that the coatings have a great potential in the surface protection of magnesium alloys.

Ti and its alloys are considered to be very promising in biological material field. But their biological activity and corrosion resistance in body fluid still need to be improved. As a novel technique for surface treatment, Micro-arc oxidation (MAO) is attracting interest from those who want to improve their implant properties through surface modification. This paper reviewed the application of MAO on biomedical Ti -alloys. The structure characteristic such as surface and cross-section micrographs, phase components, and element distribution were analyzed. The mechanical and biological properties of MAO films were further discussed on this basis. The effects of current density, voltage, and electrolyte on the structure and properties of the films were summarized.

It is thought that the PEO (plasma electrolysis oxidation) coatings are difficult to be prepared on the cast Al–Si alloys because these alloys contain lots of pure silicon phases. In the present study, oxide coatings with a thickness of about 10 μm were deposited on the substrate of the ZL109 Al–Si alloy by a PEO treatment. XRD showed that the phase composition of the coating was γ-Al2O3. SEM showed that the coating surface was porous, and the pore diameter was in the range of 1–5 μm. The cross-section view by EDS indicated that the coating matrix is quite dense, and there are few defects. Phosphorus from the applied electrolyte could be incorporated into the coating during the PEO process. A transitional zone with a thickness of about 3 μm was observed on the interface between the coating and substrate, and a high adhesive strength was expected. The average hardness of the coating was 576 HV0.025, which was 7.2 times higher than that of the substrate. High alloy element content of the substrate seems to have no remarkable and adverse influence on the structure and composition of the PEO coating.

The low bonding strength between plasma sprayed hydroxyapatite (HA) coatings and substrates is one of the problems, which should be solved. In this paper, the as-sprayed HA coatings were retreated by laser remelting. The microstructure and element analysis in coatings were studied by electron probe microanalyzer (EPMA) and the accessory of energy spectrum analyzer. The results show that the bonding state can be improved greatly after laser remelting and it is a metallurgical combination between transition layers and substrates. Generally, with the increase of laser power and the decrease of scanning speed, the bonding state between the surface and transition layer will be improved much more, but the value of Ca/P ratio will deviate much more from 1.67. In this experiment, the optimum technological parameter is that the laser power is 600 W and the scanning speed is 11.2 mm/s.

Pulsed laser deposition (PLD) is being investigated as an alternative technique to prepare hydroxyapatite coatings. In this research we studied the microstructure and phase composition of the PLD hydroxyapatite films. The surface morphology of the films is composed of droplets for which size ranges from hundreds of nanometers to a few micrometers. The cross-sectional morphology of the films shows that the films adhere to the substrate well and there are no microcracks, pores and other defects between substrate and films. The X-ray diffractometer results show that the deposited films are amorphous and the post heat treatment films consists of crystalline HA and TiO2.

Ti and its alloys are considered to be very promising in biological material field. But their biological activity and corrosion resistance in body fluid still need to be improved. As a novel technique for surface treatment, Micro-arc oxidation (MAO) is attracting interest from those who want to improve their implant properties through surface modification. This paper reviewed the application of MAO on biomedical Ti-alloys. The structure characteristic such as surface and cross-section micrographs, phase components, and element distribution were analyzed. The mechanical and biological properties of MAO films were further discussed on this basis. The effects of current density, voltage, and electrolyte on the structure and properties of the films were summarized.

Pulsed laser deposition (PLD) is a conceptually and experimentally simple yet highly versatile tool for thin films and multi-layer film research. The mechanisms, advantages and disadvantages of pulsed laser deposition were reviewed. The process and some methods to resolve the drawbacks of PLD were discussed. Pulsed laser deposition of hydroxyapatite thin films was reviewed. Simple adjustment of PLD parameters can deposit hydroxyapatite in situ in crystalline form, amorphous films or HA with other calcium phosphate phases. Compared with plasma sprayed HA coatings the pulsed laser deposition HA thin films have higher coating/substrate adhesion and have minor undesirable phases under optimal conditions. Finally, we suggested some new researches should be done.

In this paper, as-sprayed HA coatings were remelted by CW laser. The morphologies and the development of microstructures were analyzed by electron probe microanalysis. The solidification mechanism of laser remelted bioactive HA coatings is usually determined by the parameters of the temperature gradient G and the solidification velocity R. In the region of bottom pool, the G/R value is high which will result in the forming of planar crystal. With the decrease of G/R value, cellular and cellular dendrites will form. Near the surface, the coating can radiate heat to the atmosphere which will form a negative temperature gradient, consequently the structure is composed of dendrites.

Ceramic coatings were formed on a pure aluminum substrate in an aqueous solution of phosphate salt, using the pulsating micro-arc oxidation method. XRD indicated that the film composed of pure γ- Al 2 O 3. SEM showed that the surface of the film was micro-porous with 1–5 μm pores. EDS gave the element distributions of the cross-section. The result indicated that elements from the electrolyte like P could be incorporated into the film during MAO process. The microhardness test showed that the film had an average hardness of 654 HV0.025. The growth process of the Al 2 O 3 ceramic-like film was discussed on the basis of the structure analysis.

In this paper, the plasma sprayed coatings were treated by laser remelting. The morphologies, elements analysis and phases of both sprayed and remelted coatings were studied by means of electron probe microanalysis (EPMA), X-ray diffraction (XRD) and so on. The results show that the structure of the sprayed coatings is coarse, the amorphization of HA is tremendous, and the bonding state between the coating and the substrate is mechanical combination. After the sprayed coatings were treated by laser remelting in a proper conditions, the properties of the coatings are improved greatly. The microstructure of remelted coatings is columnar and cellular dendritic crystal which is homogeneous and compact, and the coating consists of HA, α-TCP and CaO phases, the Ca/P ratio of transition layer is close to 1.67, but the Ca/P ratio of surface layer is higher than that of HA because of the loss of P.

Micro-arc oxidation (MAO) is a novel technique for producing oxide films on metals like Al , Mg , Ti and Zr . A ceramic-like film containing Ca and P was deposited on Ti-6Al-4V substrate by MAO in an electrolytic solution using a pulsed power supply. XRD indicated that the film was a mixture of anatase, rutile and VO. SEM showed that the surface of the film was microporous with 1–2 μm pores. EDS gave the element distributions of the cross-section. The result indicated that elements like Ca and P could be incorporated into the film during MAO process. The microhardness test showed that the film had an average hardness of 540 HV0.025.

A modified surface layer of hydroxyapatite (HA) target was observed before and after pulsed laser deposition. Two types of HA targets were used for laser ablation. We observed that the surface morphology of the target has a very fine compacted grain structure and presents many irregularities with some microroughness and microporosity before laser ablation. The laser ablated regions can be divided into two areas: one area is porous and rough but the other is dense and smooth. The percentage of particles in the films was high for the films produced with targets that were sintered at 1200°C.

Bioglasses are promising alternatives as biomedical materials to repair or replace damaged parts of bones because of its good bioactivity and biocompatibility. It is possible to combine the bone-bonding ability of the bioglass surface with the high mechanical properties of the metallic substrate though the coating of metallic implants with bioglass. The principles and characteristics of some coating techniques, including sintering, plasma spray, sol-gel, electrophoresis deposition, ion beam assisted deposition and pulsed laser deposition, are introduced. Their current applications in preparing bioglass coatings are reviewed in detail. The future application trends are also reviewed.

Electrophoretic deposition is a good method in the preparation of hydroxyapatite/bioglass graded coatings. Its processing parameters are easy to be operated. As it is nonbeeline process, it can be used in the deposition of complex shape and porous surface. This paper reviewed the advancement of the graded coatings in recent years, concluded the principles, characters, steps of electrophoretic deposition of bioceramic coatings and analyzed influencing factors in detail, such as granularity of suspension, aging of suspension, dispersion media, PH of suspension, electricity, voltage, deposition time, pretreatment of substrate and sintering. The foreground of hydroxyapatite/bioglass graded coatings is expected.

Ceramic coatings were formed on a pure aluminum substrate in an aqueous solution of phosphate salt, using the pulsating micro-arc oxidation method. XRD indicated that the film composed of pure γ-Al2O3. SEM showed that the surface of the film was micro-porous with 1–5 μm pores. EDS gave the element distributions of the cross-section. The result indicated that elements from the electrolyte like P could be incorporated into the film during MAO process. The microhardness test showed that the film had an average hardness of 654 HV0.025. The growth process of the Al2O3 ceramic-like film was discussed on the basis of the structure analysis.

Micro-arc oxidation (MAO) is a novel technique for producing oxide films on metals like Al, Mg, Ti and Zr. A ceramic-like film containing Ca and P was deposited on Ti-6Al-4V substrate by MAO in an electrolytic solution using a pulsed power supply. XRD indicated that the film was a mixture of anatase, rutile and VO. SEM showed that the surface of the film was microporous with 1–2 μm pores. EDS gave the element distributions of the cross-section. The result indicated that elements like Ca and P could be incorporated into the film during MAO process. The microhardness test showed that the film had an average hardness of 540 HV0.025.

Pulsed laser deposition (PLD) is a relatively new technique for producing thin films. It presents unique advantages for the deposition of bioactive ceramics. The mechanism and characteristics of the technique PLD are introduced. Its applications and current research status in hydroxyapatite and bioglass thin films are reviewed. The effect of processing parameters of PLD, including atmosphere, substrate temperature, laser wavelength and target properties, on the structures and the properties of the hydroxyapatite film, is analyzed in detail. Future application trends are also analyzed.

We prepared Si-containing and Si-free coatings on Mg-1.74Zn-0.55Ca alloy by micro-arc oxidation. The dissolution and precipitation behaviors of Si-containing coating in simulated body fluid (SBF) were discussed. Corrosion products were characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD), fourier transform infrared spectrometer (FT-IR) and X-ray photoelectron spectrometer (XPS). Electrochemical workstation, inductively coupled plasma atomic emission spectrometer (ICP-AES), flame atomic absorption spectrophotometer (AAS) and pH meter were employed to detect variations of electrochemical parameter and ions concentration respectively. Results indicate that the fast formation of calcium phosphates is closely related to the SiOx(n-) groups, which induce the heterogeneous nucleation of amorphous hydroxyapatite (HA) by sorption of calcium and phosphate ions.

Hydroxyapatite films were produced by pulsed laser deposition from three kinds of hydroxyapatite targets and with different deposition times. A JXA-8800R electron probe microanalyzer (EPMA) with a Link ISIS300 energy spectrum analyzer was used to give the secondary electron image (SE) and determine the element composition of the films. The phases of thin film were analyzed by a D/max-γc X-ray diffractometer (XRD). The Fourier-transform infrared spectroscopy (FT-IR) was used to characterize the hydroxyl, phosphate and other functional groups. The results show that deposited films were amorphous which mainly composed of droplet-like particles and vibration of PO 4 3− groups. With the target sintering temperature deposition times increasing, the density of droplets is decreased. While with deposition times increasing, the density of droplets is increased. With the target sintering temperature and deposition time increasing, the ratio of Ca/P is increasing and higher than that of theoretical value of HA.

In recent years, computer and network techniques have developed rapidly and network has influenced various aspects of our lives ubiquitously and become the guarantee of social development. People also face all kinds of security problems when obtaining information knowledge conveniently. This paper mainly studies a distributed intrusion detection system model and introduces the influence of different data storage modes on detection algorithms. Finally, it puts forward different detection algorithms according to different storage modes and improved schemes aimed at traditional detection algorithms.

This paper gives the object behavior model of software, describes the interactive relationship between classes by sequence diagram and the state change of classes by state diagram. In the concrete process of modeling, this paper first uses UML modeling language to construct the structural model and behavioral model of the system and then uses integrated modeling method to establish the UML/OOPN model of software to carry out analysis and verification from another angle. Finally, it gives the general principle and design example of database design and interface design of the system.

Current network forensics systems are static and not real-time. In order to overcome the shortages, a dynamical network forensics model based on artificial immune theory and multi-agent theory, referred to as DNF, is introduced here. Comparing with traditional computer forensics methods, the new method provides the capacity that gathering real-time evidence dynamically as soon as network intrusions take place and saving the evidence in a safe way to prepare for the collection and analysis of the original evidence. In this paper, architecture of the model and the definitions of its components inspired by the immunity theory are given out. The experiment shows that it is able to insure the authenticity, integrality and validity of the digital evidence, and it is a new method for dynamic computer forensics.

The bioceramic coating is fabricated on titanium alloy (Ti6Al4V) by laser cladding the preplaced wollastonite (CaSiO3) powders. The coating on Ti6Al4V is characterized by x-ray diffraction, scanning electron microscopy coupled with energy dispersive spectroscopy, and attenuated total reflection Fourier-transform infrared. The interface bonding strength is measured using the stretching method using an RGD-5-type electronic tensile machine. The microhardness distribution of the cross-section is determined using an indentation test. The in vitro bioactivity of the coating on Ti6Al4V is evaluated using the in vitro simulated body fluid (SBF) immersion test. The microstructure of the laser cladding sample is affected by the process parameters. The coating surface is coarse, accidented, and microporous. The cross-section microstructure of the ceramic layer from the bottom to the top gradually changes from cellular crystal, fine cellular-dendrite structure to underdeveloped dendrite crystal. The coating on Ti6Al4V is composed of CaTiO3, CaO, α-Ca2SiO4, SiO2, and TiO2. After soaking in the SBF solution, the calcium phosphate layer is formed on the coating surface.

Bioactive hydroxyapatite (HA) films were fabricated by a sol–gel method and triethylphosphate and calcium nitrate were used as the phosphorus and calcium precursors, respectively. The effects of the heat treatment temperature, pH level and substrate materials on the phases and microstructures of HA films were studied by X-ray diffraction (XRD), scanning electronic microscopy (SEM) and electronic probe microanalysis (EPMA) and so on. The results show that all the sol–gel films are composed of the phases of HA, CaO, TiO2 and CaTiO3. With increasing the calcining temperature, the crystallinity of the films increases, the structure becomes more compact and changes from granular and lamellar to cellular structure, and the Ca/P ratio increases slightly because of the loss of P in the films. The addition of ammonia (adjusting the pH level to be about 7.5) can increase the HA content in the films, and the difference of substrate materials only has a little influence on the microstructure of the sol–gel films.

Inspired by the immune theory and multi-agent systems, an immune multi-agent active defense model for network intrusion is established. The concept of immune agent is introduced. While its logical structure and running mechanism are established. The method which uses antibody concentration to quantitatively describe the degree of intrusion danger is presented. The proposed model implements a multi-layer and distributed active defense mechanism for network intrusion, and it is a new way to the network security.

This paper analyzes the deficiencies of current grid trust systems based on PKI (Public Key Infrastructure), ambiguity certificate principal information, and complicated identification process. Inspired by biologic gene technique, we propose a novel grid trust model based on Family Gene (FG) model. The model answers the existing questions in tradition trust model by adopting the technology of family gene. The concepts and formal definitions of Family Gene in the grid trust security domains are given. Then, the mathematical models of Family Gene are established. Our theoretical analysis and experimental results show that the model is a good solution to grid trust domain.

Zirconia-toughened MgO-CaO-SiO2-P2O5-CaF2 glass-ceramics are prepared using sintering techniques, and a series of heat treatment procedures are designed to obtain a glass-ceramic with improved properties. The crystallization behavior, phase composition, and morphology of the glass-ceramics are characterized. The bending strength, elastic modulus, fracture toughness, and microhardness of the glass-ceramics are investigated, and the effect mechanism of heat treatments upon the mechanical properties is discussed. The bioactivity of glass-ceramics is then evaluated using the in vitro simulated body fluid (SBF) soaking test, and the mechanism whereby apatite forms on the glass-ceramic surfaces in the SBF solution is discussed. The results indicate that the main crystal phase of the G-24 sample undergoing two heat treatment procedures is Ca5(PO4)3F (fluorapatite), and those of the G-2444 sample undergoing four heat treatment procedures are Ca5(PO4)3F and β-CaSiO3 (β-wollastonite). The heat treatment procedures are found to greatly influence the mechanical properties of the glass-ceramic, and an apatite layer is induced on the glass-ceramic surface after soaking in the SBF solution.

This work is based on micro-structural performance of the Ti–B4C–C laser alloying coatings on Ti–6Al–4V titanium alloy. The test results indicated that laser alloying of the Ti–B4C–C pre-placed powders on the Ti–6Al–4V alloy substrate can form the ceramics reinforced hard alloying coatings, which increased the micro-hardness and wear resistance of substrate. The test result also indicated that the TiB phase was produced in alloying coating, which corresponded to its (101) crystal plane. In addition, yttria has a refining effect on micro-structures of the laser alloying coating, and its refinement mechanism was analyzed. This research provided essential experimental and theoretical basis to promote the applications of the laser alloying technique in manufacturing and repairing of the aerospace parts.