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The flame combustion method enables the synthesis of diamonds via acetylene-oxygen gas flame combustion in ambient air. Tungsten carbide (WC) has recently been utilized as a cutting tool in the machining industry and in dental machining applications. To obtain high-quality diamond films and achieve good adhesion on a WC substrate, diamond films are synthesized on a WC substrate by the flame combustion method. However, the surface roughness of most of the diamond films synthesized by this method increased, and it was necessary to reduce this roughness. Considering the roughness accuracy of the workpiece surface during cutting, and the performance of the cutting tool, a smaller surface roughness of the diamond films synthesized is desirable. In this study, to reduce surface roughness, the amount of diamond paste with diamond seed particles as generation nuclei was carefully varied for diamond seed attachment processing of diamond films. When diamond films were synthesized on the WC substrate surface via the flame combustion, the amount of diamond paste with diamond seed particles affected the surface morphology and surface roughness of the synthesized diamond films. Furthermore, to investigate the reason for this result, generation of nuclei on the substrate in the initial stages of synthesis and diamond seed particles on the substrate surface after the seeding treatment were observed by scanning electron microscopy. The effect of diamond seed attachment processing on the diamond films synthesized by flame combustion was studied. The relationship between the surface roughness, number of diamond generation nuclei on the substrate in the initial stages of synthesis, number of diamond particles on the substrate after the diamond seeding process, and amount of diamond paste were confirmed.

The flame combustion method enables the synthesis of diamonds via acetylene-oxygen gas flame combustion in ambient air, and this method has various advantages over other methods. However, most diamond films synthesized by this method delaminate because of thermal stress during cooling. Titanium (Ti) has recently been utilized as a dental implant in the dental industry. In this study, to improve the strength, wear resistance, and biocompatibility of dental implant surfaces, diamond films were synthesized on a Ti substrate, a dental implant material, by the flame combustion method. Moreover, to obtain high-quality diamond films and achieve good adhesion on the Ti substrate, as a pretreatment of the substrate to prevent delamination, scratch processing, in which a substrate is ground with emery paper in one direction, was performed to roughen the surface. The surface roughness of the Ti substrates was varied by scratching with emery paper of #180, #400, and #1500 grain sizes. According to these results, diamond films were synthesized on the Ti substrate surface by flame combustion. The surface morphology of the synthesized films could be altered by varying the scratching process using emery paper. Delamination of the synthesized films during the scratching process with emery paper #180 (Case A) and #400 (Case B) grain size was completely prevented. However, delamination occurred during the scratching process with a grain size of emery paper #1500 (Case C). To investigate the reason for this result, the surface roughness of the pretreated Ti substrate was observed, and it affected the surface roughness of pretreated Ti substrate affected the surface morphology and delamination of the synthesized diamond films.

A steam pressure cracking (SPC) agent is a method that can dismantle concrete safely and quickly. In previous studies, the authors showed that the direction of the crack could be controlled by the tensile stress at the induction holes and not by the compressive stress at the SPC hole. We demonstrate that the compression elastic wave changes to a tensile wave when the wave is reflected at the free surface of the induction hole. We also examined the properties of the concrete by developing an elastic wave measuring system that is difficult to break down even in high-temperature, wet, and radiation environment. The elastic wave velocity change in the four concrete types was less than 4%. It was found that the standard deviation value, σ, changed four times. Therefore, it is possible to determine the deterioration of the internal structure of concrete using the standard deviation value σ, which indicates the dispersion of the elastic wave velocity.

This study investigated a new dismantling system for concrete structures using a steam pressure cracking agent. We improved the mechanical systems such that it can drill through reinforcing steel bars. Therefore, the control method of the system and shape of the drill tip were improved. When the drill tip is stuck with chips and stopped, it is automatically pulled out and reinserted to recover the rotation. By changing the tip angle of the drill bit from 75° to 90°, it became possible to cut reinforcing bars, which were difficult to cut previously. In addition, we designed a crawler-type mechanical system and improved it such that it can be moved to the appropriate position and operated at any angle. This study revealed that the energy required for the drilling process accounts for more than 90% of the total dismantling energy. Through experiments using an impact hammer drill and observations of fracture surfaces using a three-dimensional scanner, we analysed the characteristics of reinforced concrete. In addition, the feasibility of the design for dismantling reinforced concrete was confirmed based on the determined energy associated with crack propagation.

The dismantling of large concrete structures causes environmental pollution due to the dispersion of polluted micro-particles. The purpose of this study is to develop an environmentally friendly demolition method. Steam pressure cracking (SPC) is a method that can safely and quickly separate concrete because there is less vibration compared to the explosion method. To date, the authors have shown that the direction of cracking in a small sample can be controlled by an induction hole. The principle of control is that the elastic wave of compression stress generated from the SPC reaction changes to a tensile elastic wave at the induction hole, and a crack is initiated. In this study, it was shown that the direction of crack propagation can be controlled by using induction holes in large concrete structures that are 1m on each side. Further, in the SPC method, the large amount of concrete powder generated by the explosion method is not produced, and there is no risk of secondary contamination by fine concrete powder. It was also possible to separate small pieces from the end face of the large concrete by SPC and induction holes. The area over which the crack propagated depends on the energy generated from the SPC agent, and the relationship was linear. By applying an SPC agent to dismantling large concrete structures, we can achieve controlled cracking safely and quickly without any environmental pollution.

A flame combustion method enables the synthesis of diamond using acetylene-oxygen gas flame combustion in ambient air. Recently, tungsten carbide (WC) has been used as cutting tools in the machining industry. To obtain diamond films and to achieve good adhesion on the WC substrate, diamond films were synthesized by flame combustion method. However, synthesized diamond films delaminate as a result of thermal stress during cooling. In this study, as a pretreatment of the substrate to prevent the delamination, a chemical processing was performed. The WC substrate was pretreated by chemical etching to roughen the surface. The substrate was etched in an ultrasonic bath using Murakami’s reagent. Another processing was performed using an acid solution of hydrogen peroxide, in order to remove cobalt from the substrate surface. The pretreatment periods were varied. Moreover, the effect of the pretreatment of the substrate on synthesized diamond films by flame combustion was investigated.

We develop wire saws with the diamond grains bonded to the wires for non-slurry cutting process. We invented a special product machine which has a high vacuum furnace and a special solder that contain a metallic compound. In this paper we demonstrate the finest saw wire that is 50 µm of diameter tungsten (W) wires and can perform in cutting an extremely hard material which include the diamond substrate.

A series of trials to fusion weld commercially pure titanium (CPTi) to stainless steel 304 (SS304) have been conducted using laser beam welding (LBW) and gas tungsten arc welding (GTAW). Neither technique produced adequate weld joints with LBW showing a more promising result, while GTAW yielded separation of the workpieces immediately after welding. Cracking and fracturing took place mainly on the SS304 side, which was explained by the differences in the materials&rsquo, thermal properties. Various intermetallic phases formed during welding that were identified using energy dispersive X-ray spectroscopy (EDS) and electron backscattered diffraction (EBSD) technique and were compared with an isothermal ternary phase diagram of Fe-Cr-Ti. Their corresponding hardness values are reported and correlated with alloy compositions.

This article briefly summarises previous reports as well as some recent results on welding of various titanium alloys. Titanium is available in a wide range, hence, their properties and characteristics (including welding characteristics) may also varied significantly. The alloys studied represented three major areas; they are (1): unalloyed or commercially pure titanium (CP Ti), (2): near α and α+β alloys, and (3): β alloys. From our preliminary results, it can be reported that the structure of fusion zone (FZ) and heat affected zone (HAZ) of alloys from area (1) may change but their hardness remained, arguably, the same as the as-received material. Alloys from area (2) showed an increase in hardness in the FZ and HAZ areas due to the formation of α-prime or martensite, while alloys from area (3) experienced a reduction in hardness associated with dissolution of α phase leaving only retained β in the FZ. Further investigations are required to confirm these findings. Such information are very useful so that appropriate post welding heat treatment (PWHT) can be applied to improve their properties and performance.

Milling characteristics of dental alloys have been investigated and compared. The four differently configured tools used were made of cemented tungsten carbide. Most were uncoated but one was coated with a diamond-like carbon layer. The dental alloys studied were cobalt-chrome (Co-Cr) and cobalt-chrome-titanium (Co-Cr-Ti) alloys, fairly strong alloys. There is a requirement for a reliable test to evaluate the properties of dental tools by measuring the cutting forces during milling. A full characterization of dental mills is a difficult task, because the geometry of the mills is complex, with conical multi-cutting surfaces. In this study a more comprehensive understanding of the effects of cutting rate on cutting forces was achieved by varying the cutting tool rotation speed and measuring the force on the workpiece as it was driven into the rotating tool at a fixed feed velocity. It was observed that the cutting forces were changed by varying cutting speeds. Side milling required lower forces than central slot milling. After milling the surfaces of the dental tools and dental alloy specimen were analyzed by scanning electron microscopy.

Welding characteristics of Ti-5Al-5V-5Mo-3Cr (Ti5553) alloy has been investigated. The weld joints were performed by laser beam (LBW), electron beam (EBW) and gas tungsten arc welding (GTAW). Regardless of the welding method used, the welds showed low hardness values with coarse columnar grains in the fusion zone (FZ) and retained equiaxed beta phase within the heat affected zone (HAZ). Larger grains were present at the near HAZ compared with far HAZ (near base metal). The strengths of the welded samples were lower than the base metal. Fracture occurred at the weld zones with transgranular and microvoid coalescence fracture mechanism.

This paper will demonstrate that diamond grains can be bonded to W micro-wires (AD wires) with a specially developed metal solder in a continuous process capable of producing the wire of 1000 m in length. Cutting experiments using a specially designed cutting machine have been conducted. We will demonstrate that AD wire can cut WC (HV2500) and that AD wire performs superior compared to other commercial cutting wires bonded with diamond grains using either Ni plating or resin type. It has also been found that for wire diameter less than ~ 100 µm cutting life of the wire was short and failed in a torsion fracture mode. This will be explained by comparing the friction induced torsion to the twist strength of the wire.

We propose a new high-rate reactive sputter-deposition method with two sputtering sources for fabricating TiO2 films. One source operates in a metal mode sputtering condition and supplies titanium atoms to the substrate. The other source operates in oxide mode and works as an oxygen radical source for supplying oxygen radicals to the substrate surface for promoting oxidization of titanium atoms. Each sputtering source is separated with a mesh grid from the deposition chamber, and Ar and oxygen gas are introduced separately through the titanium supply and oxygen radical sources, respectively. By using this reactive sputtering system, a deposition rate above 80 nm/min can be obtained for the deposition of TiO2 films with rutile structure.

A combustion flame method was used to synthesize diamond films on a Mo substrate. During the cooling process, most diamond films delaminated. From previous work it has been shown that a three-step method using combustion flame was viable to prevent a delamination. But it was not perfect. In order to get a better adhesion of the diamond film, distances of the flame inner cone from the substrate were changed for each step of the three-step method. The first step of the three-step method was set to the distance d=1.5mm, the second step was set to the distance d=2.0mm and the third step was set to the distance d=3.0mm, respectively, with each scratching treatment of #180, 400, 800 and 1500 on the substrate surface. The results showed that the better adhesion of the diamond film was obtained on scratched surfaces at #400, 800 and 1500. An abnormal growth of the film was able to prevent by changing the distances. The inspection by SEM and XRD showed that synthesized films on scratched surfaces at #400, 800 and 1500 by the changing distances were good diamond. It was concluded that the delamination-free diamond film could be realized by changing the distances.

The effect of sputtering voltage on indium tin oxide (ITO) film properties was investigated by using a facing target sputtering system. The reduction in the sputtering voltage was found to promote (111) plane crystal orientation and improve the surface roughness of the film, although the electrical properties of the film improved slightly. Moreover, compressive film stress could not be reduced by reducing the sputtering voltages; hence, sputter deposition at a higher gas pressure—above 1.06 Pa-was necessary to realize a stress-free film. The surface roughness, however, increases remarkably at such high gas pressure; however, a small amount of Zn was added to improve the substantial surface roughness of the film caused by the high gas pressure.

Diamond films were synthesized on a Mo substrate using combustion flame. During cooling process, the most diamond films delaminated from the Mo substrate because of their thermal expansion mismatch. To prevent the delamination, a three-step synthesis method was proposed. The first step was synthesis of the Mo2C and the diamond phases on the Mo substrate, and the second and the third steps were synthesis of the diamond phase. The interfacial stress between the film and substrate was calculated by a finite element method. According to the results, the stress in the film made by the method was smaller than that by an one-step synthesis method. The three-step method is useful for synthesizing the diamond film.

The low-cycle fatigue behavior and the relationship between the surface features in the low-cycle fatigue testing and the fatigue life of Sn-3.5Ag and Sn-0.7Cu lead-free solders were investigated at strain rate of 0.1%/s at room temperature, 80 and 120oC. In addition, the fatigue life was estimated by using the surface deformation of the solders, and image processing. And also, it was compared with Coffin-Manson type of fatigue behavior. The fatigue life of Sn-3.5Ag solder was superior to that of Sn-0.7Cu solder at temperatures, 80 and 120oC. The fatigue life determined by surface deformation indicated a close behavior to Coffin-Manson type fatigue behavior in those solders. Therefore the low-cycle fatigue life of solders could be estimated by the surface deformation.

Diamond films were synthesized on a Mo substrate using combustion flame. During the cooling process, most diamond films delaminated. From previous work it was shown that diamond films delaminated at a synthesis temperature less than 1300K (low temperature), and films did not delaminate at synthesis temperature more than 1400K (high temperature). In this study, to clarify the influences on the delamination of the interface, films synthesized at high temperature and low temperature were investigated by SEM and X-ray diffraction. The results show that in the case of low temperature, diamond films were synthesized on the Mo substrate, case of high temperature, Mo 2 C and diamond phases were synthesized on the Mo substrate. Thermally induced interfacial stress occurs due to the thermal expansion mismatch between the synthesized film and the Mo substrate. The interfacial stress by high temperature and low temperature was determined as the cause of the delamination. Thus, the interfacial stress of each synthesized temperature was calculated by a finite element method. The results show that the interfacial stress in the film synthesized by high temperature was smaller than that by the low temperature. As the buffer phases prevent the delamination, synthesized films by high temperature will be useful as hardcoating layer for a metal surface.

A new method of bonding diamond to metal with active solder has been developed. This method was then used for making micro-cutting wire saws capable of cutting composite materials with high hardness. This cutting process is an environmentally friendly process, as diamond grains loss and hence pollution is minimum. The active solder contained titanium hydride ( TiH 2). Titanium hydride dissociates to atomic Ti and H at high temperatures improving wetting between the solder metal and diamond grains and hence high bonding strength can be obtained. An example of using the new wire for cutting a typical IC chip is given. We believe this environmentally friendly micro-cutting process will be widely used in the future.

The low-cycle fatigue behavior on Sn-0.7Cu lead-free solder as-cast and Sn-Pb eutectic solder as-cast were investigated at a strain rate 0.1%/s under various temperatures of 25, 80 and 120oC. In addition, the relationships between the surface feature in the low-cycle fatigue test and low-cycle fatigue life of those solders at 25oC were investigated by image processing. The low-cycle fatigue life of Sn-0.7Cu decreased when the temperature increased. And the fatigue life of Sn-0.7Cu was better than that of the Sn-Pb eutectic solder at the temperatures of 25 and 80oC. The low-cycle fatigue behavior on the solders investigated followed Coffin-Manson equation. The fatigue ductility coefficient of Sn-0.7Cu was found to be affected by the temperature. The surface deformation as fine meshes in the low-cycle fatigue test of Sn-0.7Cu did not appear until 10% of the fatigue life. Although it was over 10% of the fatigue life, the surface deformation that was caused by micro cracks and coalesces occurred with the increasing number of cycles. The relationships between the surface feature in the low-cycle fatigue test and the low-cycle fatigue life on Sn-0.7Cu and Sn-37Pb solders were discussed.

The surface scratch resistance, damage evolution and damage detection during microscratching of pure AlN and AlN with an Al2O3 oxide layer (∼0.1 μm) were investigated. The microscratch experiments were performed in a progressive load-ramped mode where the load was linearly increased from 0 to 3 N as the scratch progressed with a loading rate of 0.2 N/min. The experiments resulted to two different failure mechanisms; Ductile scratching and fracture dominated scratching. In the case of pure AlN, inconsistent different kinds of damages were found to initiate at low critical load measured as 0.30 N. This critical load was also found to decrease with increasing the surface roughness, material density and grain size of AlN. In the case of pure AlN with an Al2O3 oxide layer, the critical load for crack initiation was measured as 0.45 N, higher than pure AlN. This critical load was found to generate uniform discontinuous chipping. The distance between these defects decreased and the failure mode gradually transformed to continuous chipping as the scratch progressed. The surface modification of AlN with the use of an Al2O3 oxide layer was found to improve the tribological properties of AlN.

Nanomechanical characterization of LiNbO 3 –Ti(20 nm)–Pt(10 nm)–Au(100 nm), substrate/multilayers, was studied by depth-sensing diamond nanoindentation/scratch technique. Nanoindentation tests were performed using a Berkovich indenter of 50 nm of the tip radius. The average measured values of hardness and elastic modulus of each film were evaluated discretely. It was found that at diamond penetration depth exceeding 20% the thickness of the film, the mechanical properties of the film were influenced by those of the LiNbO 3 substrate. Discontinuities were also observed in the loading part of the load–depth curves, and were found to be in correlation with the substrate/films practical adhesion. Nanoscratch tests were performed using a cube-corner diamond tip. They consisted mainly of three failure modes: ductile, ductile to brittle transition, and brittle. The critical load for practical adhesive failure measured for the LiNbO 3 –Ti(20 nm) was found relatively higher than that measured for the LiNbO 3 –Ti(20 nm)–Pt(10 nm).

This paper deals with the welding chamber applied to gas-shielded arc welding under the environment of strong wind. Basically, gas-shielded arc welding method itself is established technology but it is assured the welding quality only in calm environment. Generally, it is necessary to keep the wind velocity at 1.5m/s or less. The fluid chamber reported in this paper can protect against the wind velocity at 7m/s by coaxial jet what is called air curtain. This original coaxial jet generates a laminar swirl flow formed by plural "Partitions" arranged inside of the slit nozzle and assures the welding atmosphere in calm.