The performance and structure of chromate conversion coatings with phosphate or silica additives applied on the electro-galvanized steel have been investigated, and double roles of these additives in the film structure were proposed.
It was found that phosphate reduces hexavalent chromium content, which is the possible reason for improvement of appearance and the adverse effect on corrosion resistance. While silica was found to form a bulky layer that can disperse yellowish hexavalent chromium and hold stable zinc corrosion product within the film, which can be related to the improvement of appearance and corrosion resistance.
Phosphate forms a less-polor outer layer which repels paint, water and fingerprint. This is ascribable to the poor paint adhesion, relatively good wet adhesion and excellent fingermarking resistance of phosphate containing chromate. On the other hand, silica forms a polar outer layer which attracts paint, water and fingerprint. This is why the silica-containing chromate showed good paint adhesion as well as poor wet adhesion and a great amount of fingerprint adhered to its surface.
The optimum film structure was designed based on these results.

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Spangles formed at hot-dip galvanized steel were classified and the distribution of Pb and Al, which were impurity and additional element respectively in molten zinc bath, on the spangle surface was investigated. The hot-dip galvanized Al-killed steel was produced with gas reduction type hot dipping testing aparatus in which steel sheet was cleaned by heating in reducing atmosphere and dipped into molten zinc bath which contained 0.25 wt%Pb and 0.17 wt%Al. X-ray Laue method was used for determination of crystal orientation and EPMA was used for the measurement of distribution of Pb and Al at the spangles.
The main results of the study are follows:
(1) The spangles are classified from the point of view of the crystal orientation and the appearance into the seven types as follows,
Fern I, Fern II, Mirror, Frost, Half fern, Feather, Triangle.
(2) The direction of the straight boundary of the spangles coincide with the projected direction of preferred crystal growth orientation (<1010>) on the spangle surface.
(3) Spangles are classified into α type and β type from the point of view of the inclination of c-axis (<0001>). The c-axis of α type spangle is inclined to the straight boundary of the spangles and the c-axis of β type spangle is inclined to the reverse direction.
(4) The amounts of Pb and Al at the spangle surface vary with the types of the spangle.
(5) The spangle with the larger amounts of Pb and Al has less brilliance.

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Influence of drying temperature on states and physical properties of a dry-in-place type chromate coating which contains Cr (III), Cr (VI), and PO₄^3- were investigated by thermal analysis method. And also the relationship between thermal states and corrosion resistance was studied.
The result of the differential thermal analysis method with the chromate coating at wide range of temperature shows characteristics reactions of inorganic materials.
Endothermic reaction at a range from 85°C till 200°C and exothermic reaction from 200°C till 300°C were found. The chromate coating can be divided into three states from the result of this thermal behavior.
The result of corrosion test of this chromate coated galvanized steel between visual and electrochemical method exhibits the best performance with drying at the end temperature of the endothermic reaction.
It was also proved by values of chromium fixed ratio in coating that chromate coating had several thermal states and exhibited different physical properties as adhesion strength etc.

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In composite-type vibration-damping steel sheets, surface pre-treatment for the skin steel sheets has been examined and discussed for cold-rolled steel sheets, chromate-treated steel sheets, and electro-galvanized steel sheets (EG). The evaluation was based on the bond interface durability produced during salt spray testing up to 1000 h. Chromate treatment was confirmed to be the best surface pre-treatment for skin sheets, because it improves the primary (pre salt-spray-test) adhesion strength and prevents decreased secondary (post salt-spray) adhesion strength. EG has no ability to suppress the decrement of secondary adhesion strength, because Zn dissolves in water and edge-creep goes on. The failure mode in T-peel test changes from cohesive to inteface failure with decreasing secondary adhesion strength and with the occurrence of edge-creep.

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There is an increasing demand for steel sheet that should be completely free from oiling and degreasing during the forming operation in order to improve working environment and hence global environment ; In order to achieve this we studied a lubricated galvanized steel sheet, which has a thin organic film consist of base resin, lubricant and silica for the anti-corrosive agent on the chromated upper layer.
A lubricated galvanized steel sheet requires not only good lubricity but also good resistance to mechanical damage that causes deterioration of surface appearance. From the point of the improvement of resistance against mechanical damage, an organic film has high level of mechanical strength to reduce powdering by sliding, and has adequate softness that allows the film to follow to the press deformation well. The tensile strength and elongation of various polyurethane resin films were measured. On the basis of the test results, it was concluded that blended aromatic resin base polyurethane and aliphatic one was bridged by hardener has good mechanical properties to provide excellent surface appearance.
Polyethylene lubricant in the film had good coefficient of friction at wide range of temperature, as compared with other solid lubricant. From the point of the balance of corrosion resistance and surface appearance after forming, 1015wt% silica content in the film had better performance.

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There is an increasing demand for steel sheet that should be completely free from oiling and degreasing during the forming operation in order to improve working environment and hence global environment; In order to achieve this we studied a lubricated galvanized steel sheet, which has a thin organic film on the chromated upper layer.
A lubricated galvanized steel sheet requires not only good lubricity but also good resistance to mechanical damage that causes deterioration of surface appearance. The reason why the appearance of the steel sheet deteriorated was investigated by considering that this is caused by sliding and deformation. The draw bead test which simulate both sliding and deformation components of forming process was used as a simulation testing method to study deterioration of the appearance.
From the point of the improvement of resistance against mechanical damage, an organic film has high level of mechanical strength to reduce powdering by sliding, and has adequate softness that allows the film to follow to the press deformation well. The tensile strength and elongation of various films were also measured. On the basis of the test results, it is concluded that thermosetting polyurethane resin has good mechanical properties to provide excellent surface appearance.

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溶融亜鉛メッキ鋼板 (HDG板) の表面処理剤として, 無機超微粒子 (100nm以下) 含有アクリル複合樹脂 (複合樹脂) を適用し, 鋼板に対する耐食性, 塗装下地性について検討した。皮膜厚さ1～0μmの複合樹脂被覆鋼板およびアミノアルキド塗料塗装鋼板の塩水噴霧試験, 乾湿サイクル腐食試験, 沸水浸せきによる湿潤試験の結果, SiO₂複合樹脂皮膜は, 他の無機超微粒子のA1₂O₃, BaSO₄, CaCO₃, Fe₂O₃, TiO₂, ZnO複合樹脂皮膜に比べて, 耐食性および付着性とも著しい効果を示すことが判明した。
このSiO₂超微粒子は, その製造履歴, 粒子の比表面積, 表面層の水酸基 (≡SiOH) が耐食性に関係し, 乾式法より湿式法で製造された粒子, 比表面積が大きく水酸基の多い, 親水性の粒子が有効であった。また, 複合樹脂皮膜の膜厚が厚いほど, 耐食性は良好であった。
クロメート処理HDG板に対する複合樹脂皮膜の効果は, クロメート皮膜との相乗効果によって, 上記の皮膜処理HDG板に比べて, いずれの複合樹脂皮膜とも, その耐食性が塩水噴霧試験で数十倍に達し, この系でもSiO₂複合樹脂皮膜が効果的であった。SiO₂微粒子の種類, 膜厚の効果は, 上記の皮膜処理HDG板と同じ傾向を示した。
これらの結果から, SiO₂複合樹脂皮膜はHDG板との付着性が良く, HDG板の塗膜下腐食を抑制する効果を有することが予想される。

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 From ancient times, mountains have been worshiped in Japan. Mt. Fuji is archetypal, and the stone huts that served its pilgrims can be regarded as the original form of current mountain huts. Nowadays, since Mt. Fuji is a World Cultural Heritage site, its huts are required to be historically based. Although some historical materials describe the stone huts that existed from the Edo to the beginning of the Showa era, the changes stone huts underwent during the era of tourism after the establishment of Fuji Hakone National Park remain unclear. To investigate these changes, we examined historical materials, held interviews, and conducted field surveys on the Yoshida trail, from where great numbers of pilgrims who belonged to Fuji-ko societies made worship-ascent.
 In Showa 6, the National Park Act was established to preserve the natural landscape, promote the welfare of the people, and attract foreign tourists. In Taisho 12, Mt. Fuji became a candidate for inclusion into the park. Yamanashi Prefecture and local people embarked on campaigns to establish the park and increase tourism. In Showa 11, Fuji Hakone National Park was established. During the Pacific War, national parks were used as training grounds. An increase in the number of climbers training and ascending Mt. Fuji to pray for victory was observed. Under these conditions, the stone huts that seemed to have kept their original form since the Edo era underwent gradual changes. Traditionally, huts had a wooden frame structure and were covered with wooden boards. Stones were piled on the roof and around the walls, which had one or two sweep-out windows. From the prewar to the postwar period, almost all stone huts changed their fa?ade by incorporating waist-high windows. Furthermore, some of the piled-up stones were removed on about half of the huts, and exposed wooden boards were either covered or replaced with galvanized iron.
 About 3 years after the war, tourism in Yamanashi Prefecture returned to prewar levels. In Showa 27 and 39, a mountain bus line and the Fuji Subaru Line (a motorway) serviced the fifth station, dramatically changing the approach to climbing Mt. Fuji on the Yoshida trail. The wooden huts and sections of the trail below the fifth station fell into disrepair, while more than half of the stone huts above the fifth station were either newly constructed or renovated. The traditional floor plan of the stone huts had a main room (hiroma), which had wooden floors and a fireplace. The newer huts had larger dimensions and eave heights compared with huts at the end of the Edo era. Three patterns of change were evident. First, new huts were built with a roof truss structure (yogoya). Second, the new huts were built beside traditional stone huts with Japanese-style roof structures (wagoya). Third, stone huts were renovated. Almost all of the stone huts introduced the roof truss structure to allow for an open floor plan, waist-high windows for an open fa?ade, double bunks to accommodate more climbers, and new facilities, such as water filtration systems and curtains to ensure the safety and privacy of climbers.
 A questionnaire survey in Showa 30 showed that only 2% of climbers were on religious pilgrimages, indicating that the changes to the stone huts were in response to the growing tourism industry. In the Edo era, stone huts were a kind of symbol of Mt. Fuji religious pilgrimages; however, in the early Showa era of tourism, the owners of the stone huts removed the stones as they modernized their huts.

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 From ancient times, mountains have been worshiped in Japan. Mt. Fuji is archetypal, and the stone huts that served its pilgrims can be regarded as the original form of current mountain huts. Nowadays, since Mt. Fuji is a World Cultural Heritage site, its huts are required to be historically based. Although some historical materials describe the stone huts that existed during the Edo era, the changes stone huts underwent during the era of great transition from worship-ascent to alpinism remain unclear. To investigate these changes, we examined historical materials, held interviews, and conducted field surveys on the Yoshida trail, from where great numbers of pilgrims who belonged to Fuji-ko societies made worship-ascent.
 At the start of the Meiji era, although Fuji-ko was reorganized after the separation of Shinto and Buddhism, stone hut owners, who had recorded the location and scale of each hut since the late Edo era, were still permitted to manage them under the Yamanashi prefectural governor. Since the middle of the Meiji era, railway lines to the foot of Mt. Fuji were gradually connected. By increasing the number of climbers, and even pilgrims, Yamanashi and Shizuoka Prefectures issued regulations for individuals living on the mountain to ensure the safety of climbers and improve sanitation. Chiyozaburo Takeda, the Yamanashi prefectural governor, then decided to repair the trail and renovate some facilities, especially at the eighth station, to make Mt. Fuji an international tourist site. In Meiji 40th (1907), one stone hut was renovated into a post office, a police box, and a first aid station, and the other two into lodgings. A model lodging designed by government engineers, the Fujisan Hotel, was then built. It had a completely different appearance from stone huts (structure, lighting and ventilating facilities, two berths, etc.). With cooperation between the government and some local citizens, the Fujisan Hotel was realized as modern architecture. Some oshi and locally influential people responded to Takeda by founding a stock company to manage the huts at the eighth station. The former had quickly changed their shukubo to ryokans, and the latter had built a fortune in business from the Edo era. As a model, Takeda had expected other stone huts to develop independently, but this did not go as planned.
 By the end of the Taisho era, the stone hut sites where trails met at the fifth, sixth, and the eighth stations were expanded. Although the size of these huts may also had changed, many seem to have retained their forms from the late Edo era. On the other hand, at the seventh station, where no trails met, only one-third of the stone huts expanded their sites, in particular, the one hut had changed the facade with no cinders stacked around the wall, i.e. more open. These changes were managed by the owners of the stock company. In addition, around the time of the Great Kanto Earthquake in Taisho 12th (1923), a mountain hut and a post office were built at the eighth station, and a king post was introduced by the owner of the Fujisan Hotel. Through the Taisho era, these changes were led by those concerned with the stock company at the eighth station.
 During the Edo era, oshi and their servants, hyakusho, owned and managed the stone huts. During the Meiji and Taisho eras, people had different positions and ideas compared with past owners; in other words, extrinsic motivation changed the old customs and opened the door to modernization. In this way, the equalities among the stone huts maintained by oshi and hyakusho during the Edo era might have been lost.

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