By immersing in a chloride salt bath with added chromium powder at temperatures lower than 873K for 1-4hours, chromium carbonitride coatings thick enough for practical application were formed on various pre-nitrided steels. Wear- and seizure- resistance of steel coated by this method was superior to those of hardened steel and nitrided steel, and comparable to those of steels coated by PVD and high temperature TRD, CVD. Oxidation resistance improvement by this method was close to that of chromium carbide coated steel by high temperature TRD. However, toughness of steel thus coated was inferior to that of hardened steel. The coating was concluded to be applicable to aluminum die casting and aluminum extrusion dies.
The composition of the bath was 40g/dm3 NiSO4·6H2O, 50g/dm3 C6H5O7Na3·2H2O and 35g/dm3 NaPH2O2·H2O. Bath volume was used 50cm3. Substrate was an oxgen-free copper plate and its active area was 1cm×5cm×2. Two methods of ultrasonic irradiation were used. One was irradiation during plating, the other was one hour irradiation before plating (ultrasonic treatment bath). The deposition rate of Ni-P film increased with the ultrasonic irradiation. The most efficient was ultrasonic irradiation during plating, followed by ultrasonic treatment bath then non-ultrasonic irradiation. The most efficient frequency was 45kHz. P content of Ni-P films was reduced with ultrasonic irradiation in the order 100>28>45kHz. P content was reduced with increasing thickness at 45kHz. But P content increased in the ultrasonic treatment bath. P content increased under 2.5μm, increased steadily from 3 to 6μm and increased slowly over 6μm in the non-ultrasonic and ultrasonic treatment baths. Hardness increased with ultrasonic irradiation, in the order 100kHz (81Hv)<28kHz (88Hv)<45kHz (96Hv). Corrosion resistance increased with the ultrasonic irradiation, and incresed with heat treatment.
This study investigated the electrodeposition of Mo from anhydrous MoCl5 and Na2MoO4 in various organic solvents; HCONH2, HCONH2-CH3CONH2, OCH2CH2CH2CH2, HCON (CH3)2, CH2(CH2)4NC; N(CH2)2CH2 and (CH3)2SO. Bright deposits of Mo were obtained from 15g/L∼40g/L Na2MoO4, HCONH2 or HCONH2-CH3CONH2 under 30A/dm2, 100°C and 60∼90min, plating time. The deposits obtained were Mo-Pt alloy films.
The structure of Ni-Mo alloys electrodeposited from ammoniacal tartrate baths was discussed in terms of their codeposition behavior. The results obtained are as follows: (1) With increasing Mo content in the alloys, the partial current efficiency of Mo first increased and then decreased after a maximum was achieved. This showed the existence of two characteristic alloy compositions, i. e., a Mo content at a maximum partial current efficiency of Mo and one at the upper limit of Mo deposition. (2) Alloys of lower Mo content were found to consist of α-Ni solid solution by X-ray diffraction analysis and the diffraction peaks became broader with increasing Mo content. (3) From SEM observation of the surface appearance of the deposits, the most compact and smooth deposits were found in alloy which gave the maximum partial current efficiency of Mo. With a further increase in Mo content, blackish deposits were observed in the alloy. (4) TEM study also revealed that the main phase of the electrodeposited Ni-Mo alloys was α-Ni. When the Mo content exceeded the value of the maximum partial current efficiency of Mo, the X-ray diffraction patterns of the deposit showed broad and diffuse peaks similar to those from an amorphous phase. However, the alloys were found from TEM observation to consist of α-Ni crystallites smaller than 30nm in diameter and fine particles of MoO2 crystals. This finding supports the multi-step reduction mechanism based on intermediate Mo (IV) compound in the codeposition of Mo with Ni.
La-Ni alloy film can be formed on a nickel substrate in eutectic KCl-LiCl molten salts with 10mol% LaCl3 by the electrodeposition method. A surface film with 30μm thickness was obtained by this method at 923K for 1hour. The composition of the alloy films depends on the temperature, consisting of LaNi3, La2Ni7 and LaNi5 between 773K and 923K. The Vickers hardness of the alloy films obtained by this method was less than the LaNi5 ingot specimen. The alloy films show better hydrogen absorption and less pulverization comparing to the LaNi5 ingot.
The effects of cationic polymer additives on gold electrodeposition citric acid baths and the corrosion resistance of gold plating films were investigated by physicochemical methods. In a bath containing a small amount (5ppm) of poly (ethyleneimine) derivative such as ethoxy-modified (PEIEt), film porosity decreased significantly and deposition efficiency decreased slightly. The lower film porosity in the bath with PEIEt is due to the fine structure of grain and the leveling effect of surface. In polymer additives such as PEIEt, the effective property given the lower film porosity and higher deposition efficiency can be obtained by the balance between continuous adsorption ability and steric hindrance of polymer.
The synergistic effect of organic additives and pulse-current plating in a gold electrodeposition citric acid bath was investigated. Then the corrosion resistance of the gold plating film was evaluated by physicochemical methods. By the synergistic effect, the bath containing 2, 3-diaminopyridine (23DAmPy) produced both lower film porosity and higher gold deposition efficiency. These properties are due to the moderate physical adsorption of 23-DAmPy, whose structure is susceptible to cation, under pulse-current plating. In any event, the synergistic effect appears in pulse-current plating in the bath containing organic additive.
Nickel sintered compacts with micro-throughpores which may be used as a filter element in the semiconductor production process were prepared. Mixed with the nickel powder of 3∼7μm grain size, acrylic particles of 0.4μm grain size and wax were compacted and the green compacts sintered in a mixture of argon and hydrogen gases at 973∼1373K. The effect of the amounts of acrylic particle and wax as binders and sintering temperature on the structure, pore size and pore density of the compact were examined. The optimal amount of acrylic added to nickel powder was fond to be 5∼7.5 parts per hundred plus a very small amount of wax. Nickel compacts sintered at 973∼1173K had a maximum pore size of 1∼3μm and an apparent pore ratio of 20∼45%. Characteristic curves of pressure drop versus air flow rate for several compacts measured at 298K were presented.
An investigation has been conducted into the electrodeposition of Nb-Sn alloy from ambient temperature molten salt electrolytes of an SnCl2-NbCl5-BPC (1-butylpyridinium chloride) system and an Sn-NbCl5-BPC system. The two component base electrolytes of NbCl5-BPC were first investigated, then three component systems were done. The deposition of Nb-Sn alloy was possible from an NbCl5-BPC melt with SnCl2. An Nb-Sn alloy containing 14.8wt%Nb was deposited from a 53.8mol%SnCl2-7.7mol%NbCl5-38.5mol%BPC bath at 5mA·cm-2 and 130°C. The Nb-Sn alloy deposited from the NbCl5-BPC melt with Sn metal contained a higher weight percent Nb content than that deposited from the NbCl5-BPC melt with SnCl2. The Nb content increased by increasing the NbCl5 concentration in the melt. An Nb-Sn alloy containing 27.9wt%Nb was deposited from the 7.7mol%Sn-15.4mol% NbCl5-76.9mol%BPC bath at 40mA·cm-2 and 130°C.
Al-Ti alloy-electrodeposition in AlCl3-NaCl-KCl eutectic molten salt bath at 200°C has been studied using a flowing cell. The Ti content in deposited film increased with addition of TiCl3, and smooth deposit of Al-40.2%Ti was obtained at current density as high as 2000A/m2. The crystal structure of deposited films were found to change from cubic-Al, tetragonal-Al3Ti to tetragonal-AlTi with an increase in Ti content. Ti could not co-deposit unless Ti2+ was in bath, therefore, the addition of Al powder, which reduced Ti3+, was necessary. Electrochemical behavior of the Ti ion in the bath was studied by the electrochemical polarization technique. The reduction of Ti3+/Ti2+ (0.4V, vs. Al) and Ti2+/Ti0 (0.05V, vs. Al) were observed. Furthermore, a process using TiCl4 gas as the Ti source was demonstrated. Consequently, it can be considered that this molten salt electroplating system is one of the most feasible methods of producing Al-Ti alloy electroplated products.
Electrochemical Implantation of Si and formation of suicide have been achieved at 450°C using the new electrolyte LiCl (54.5mol%)-KCl (40.5mol%)-LiF (5.0mol%), which contains K2SiF6 (0.05-0.07mol%). The electrode potential of Si (IV)/Si (0) (Si (IV) 0.06mol%) has been determined to be 1.6V vs. Li+/Li. When the iron and nickel electrodes were cathodically polarized to a more negative potential than 1.6V, silicon was implanted onto the surface of both of the electrodes. Powdered silicide was obtained when iron and silicon were codeposited on the iron electrode from the same electrolyte containing both K2SiF6 (0.05-0.07mol%) and Fe (II) ion (0.01-0.02mol%) for several hours.
Galvanostatic pulse is one of important techniques for making multilayers. The basic preparation condition of Cu/Ni multilayers from chloride bath was investigated using a galvanostatic pulse method. Smooth and finely layered deposits were obtained with the additation of peptone.
The electrodeposition of gold from nonaqueous solutions was studied with an electrochemical methods, and the morphology, preferred orientation and grain size of the deposited gold were analyzed by electron microscope or X-ray diffraction. The properties of the gold deposits were remarkably affected by differences in bath conditions. The hardness and contact resistance of gold film obtained from an organic solvent bath were lower than those of film obtained from an acidic bath containing a small amount of cobalt ion. It is thought that the electrodeposited gold film from a formamid solution may be applicable to connecting materials, since its hardness may be increased by keeping the current under control.