Authors had reported already that the spreading of BAg alloy on mild and stainless steels could be improved by adding small amounts of NiCl2 or FeCl3 to KCl-LiCl cut. salt flux. In this study, then, when a 18Cr-8Ni stainless steel plate was pre-coated with the mixed salt fluxes and was heated, the corrosion products formed on the plate surface were analized by SEM and X-ray diffractometer. On the other hand, a spreading test of BAg-5 on the same treated plate was done, using only KCl-LiCl eut. salt flux.From these experiments, the effect of used fluxes on the spreading of BAg-5 was concluded as follows;1) The addition of NiCl2 to KCI-LiCl eut. salt promotes the dissolution of chromium and iron from the stainless steel and the resultant corroded surface becomes spongy intermetallic compound, FeNi3, furthermore, the particles layers of nickel were precipitated on the compound owing to electrochemical reaction.2) The addition of FeCl3 to the eut. salt also promotes the corrosion of stainless steel and the surface becomes the spongy compound, FeNi3.3) The spread area of BAg-5 on the particles layer of nickel was considerably larger than that on the compound, FeNi3. This result showed that the wettability of intermetallic compound, FeNi3, is not superior to the each wettability of both constituent elements, Fe and Ni.4) The spread area of BAg-5 on the particles layer of nickel was larger than that on a nickel plate, because the former was larger than the latter in a real surface area to be wet. Furthermore, since the spread area depended on the total surface area of particles distributed on the most outside layer, the amount of NiCl2 necessary to form mono-particle layer was considered to be about 10wt%.5) "De-chromiumnisztion" phenomenon on the surface of stainless steel may be one of the important effect of flux used.
In previous papers, on aniline hydrochloride flux action of soldering, it has been shown that molten aniline hydrochloride reacts with copper to give CuCl2 and copper complex, which react with molten solder to give metallic copper.Successively, this copper dissolves into the molten solder and a thin Cu-rich layer is formed on the surface of molten solder. The wetting of the solder on copper plate is improved through the reaction and the dissolution of Cu into molten solder.In this report, the flux action of various inorganic metal salts (chloride, sulfate and nitrate) on soldering was studied in the relation between the reaction of flux with Sn and wettability of Sn solder on Cu plate.The results of flux action of various inorganic metal salts are summarized as follows:1) The reaction of molten Sn with metal salt and the effect of metal salt on spreading are dependent mainly on an electrochemical series.2) The improvement of spreading by inorganic metal salts may be ascribed to the reaction of molten Sn with metal salt and the dissolution of the metal into molten Sn from the flux.3) The difference in effect on spreading by inorganic metal salts is acknowledged to some degree.
The purpose of this study is to investigate flow pattern around mosquito's wing while it is beating. We constructed on experimental apparatus to simulate beating motion of mosquito. An enlarged scale model experiment was carried out using a very low speed wind tunnel under the condition that Reynolds number and Strouhal number were made equal to those of real mosquito. The flow around the wing model moving up and down was visualized using smoke and laser light sheet and it was analyzed by a PIV system. Unsteady vortices were observed to be generated on the upper surface of the model wing in the period of downstroke. We compared the vortices each other on three different kinds of enlarged scale models (8.10.12.5times). The results suggested that it was better to simulate the left and right wings in one body by a plate model because of bilateral symmetry
There are three fundamental points to understand the wettability of molten soders. Namely, (a) The magnitudes of surface energy in mother metal or molten solder and interfacial energy of mother metal/molten solder are closely related to the propriety of wettability.(b) The alloying tendency between mother metal and molten solder or the magnitude of diffusion power of molten solder to mother metal is related to propriety of wettability.(c) The magnitudes of alloying energy or potential energy due to gravity are related to propriety of wettability.Generally, wettability varies with chemical composition of soft solders, fluxes, mother metals and surface condition, heating temperature or atmosphere. And necessary condition to get perfectly wet is the following equation.σs>σLS+σL⋅cosθwhere σs; surface tension of mother metal.σLS; interfacial tension of solder/mother metal.σL; surface tension of solder.θ; equilibrium contact angle of solder/mother metal.Accordingly, in this test, authors have measured the spread area of solders combined with various fluxes and investigated the surface tension of mother metal, interfacial tension of solder/mother metal, surface tension of solders and viscosity of fluxes which have effect on the magnitude of spread area. As fluxes, ZnCl2, ZnCl2-SnCl2⋅2H2O, ZnCl2-NH4Cl, ZnCn2-NaCl, ZnCl2-KCI binary system fluxes and ZnCl2-SnCl2. 2H2O-NH4Cl ternary system flux are used. As solders, Sn-Pb, Pb-Cd, Sn-Bi, Sn-Cd, Sn-Zn and teernary solders are used.The results obtained from above investigations are as follows.(1) The spread area of eutectic solder at 350°C is little affected by flux such as ZnCl2-NaCl or ZnCl2-KCl.(2) The spread areas of Sn-Pb, Zn-Cd and Pb-Cd solders are comparatively satisfactory with ZnCl2 flux at 350°C. And in the case of Sn-Pb, Sn-Bi, Sn-Cd, Pb-Sn and Pb-Cd, i.e., two component solders, the spread area with ZnCl2:NH4Cl=2:1 binary flux at 350°C has a comparativey larger value than with ZnCl2 only.(3) With regard to the effects on spread area of the 3rd alloying metals in eutectic solders, the effects of these metals are not a negligible factor; especially, the spread area is increased by addition of As to eutectic solders. As the quality is deteriorated by addition of As, Bi and Zn, addition of these metals is to be avoided.(4) When Sn70Wt%-Zn30Wt%, Sn70Wt%-Bi30Wt%, Sn70Wt%-Pb30Wt% and Sn70Wt%-Cd30W% i.e., two component solders combined with ZnCl2;SnCl2⋅2H2O=2:1 and ZnCl2:SnCl22H2O:NH4Cl=2:1:1 system fluxes are used, the temperature dependency of the spread area of solders is relatively high in range from 300 to 400°C. The spread area of above solders combined with ZnCl2:SnCl2⋅2H2O:NH4Cl=2:1:1 ternary flux has a larger value than ZnCl2:SnCl2⋅2H2O=2:1 binary flux.
This paper discusses the method of a focus servo system design for a video disk player.For a conventional focus servo system, a phase delay-lead compensation has mainly been used because we owned much know-how about it. Gain variations of each optical head have been eliminated by gain adjustment. This adjustment, however, introduces the problems, such as uneven control performance and higher cost.We considered applying the robust model matching method, which enables us to omit the gain adjustment. This method brought in some difficulties like reconciling robust stability with low sensitivity and reducing the degree of controllers. We overcome them by using a reduced model and properly designing the model matching system and the robust filter. We also confirmed the validity of this method by experiments.
Patient is 40 years old with history of two deliveries and the last delivery was at the age of 28 years, but she had no irregularity with mestruation. Her chief complaint was a hypogastric tumor. On examination at our clinic we found: the size of corpus uteri, about normal; felt an immovable, soft but solid tumor as large as a head of adult in the hypogastric region; and it was diagnosed as a intraligamentary solid tumor of ovary.Upon laparotomy we found no abnormalities in both adnexa and corpus uteri itself, but with the progress of operation we uncovered a giant myoma of the uterine cervix, measuring 19cm×25cm×20cm, and weighting 3.2kg, which grew out of the right wall fo the uterine cervix with the pedicle as big as the size of a pencil. Myomectomy and subtotal hysterectomy was performed.It is generally accepted that the cervical myoma of uterus is relatively rare, occupying only about 5 per cent of all uterine myomas. Furthermore, with a better understanding for surgery on the part of general public, the incidence of giant myoma of the uterine cervix has become still rarer.As for the symptoms when such a tumor reaches beyond a certain size, increased frequency of urination and corstipation are said to occur. Fortunately no such symptoms could be observed in the present case, and just as in this case, such a myoma is quite difficult to differentiate from the solid tumor of ovary and it is only after operation that it can be diagnosed correctly as a myoma of the uterine cervix. As for the relationship between the pregnancy and the delivery, it is generally the same as in the case of other uterine myoma. For the cure of such a case surgery is the sole therapeutic measure.
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