A silica overlayer was prepared on γ-alumina by a method of chemical vapor deposition (CVD) of silicon alkoxide using preadsorbed benzaldehyde and R-naphthaldehyde as a template. Infrared spectroscopy confirmed that the preadsorbed benzoate anion species remained after the deposition of silica, indicating that silica was deposited on the exposed surface of alumina. On the basis of the adsorption property of modified alumina, it is considered that the silica overlayer had a vacancy whose size was as large as the template molecule. 29 Si NMR spectroscopy showed that the Si species deposited using the template was Si(OAl)1(OSi)1(OH)2 or Si(OAl)2(OSi)1(OH)1, while the deposition without the template formed such a species as Si(OAl)1(OSi)3 and Si(OAl)1(OSi)2(OH)1 bonded via a two-dimensional siloxane network. Lack of activity for double-bond isomerization of 1-butene to 2-butene on the silica overlayer prepared using the template was consistent with the previous results that the two-dimensional network of siloxane on the alumina surface induced Brønsted acidity on the Al-O-Si-OH species. Both the adsorption and acidic properties on silica-deposited alumina using R-naphthaldehyde were different from those on the sample prepared using benzaldehyde, showing that the structure of the silica overlayer was controlled by the template molecules.

Two kinds of α- Fe 2 O 3 catalysts supported on χ- Al 2 O 3 and γ- Al 2 O 3 were synthesized. α- Fe 2 O 3 was prepared from α- FeOOH . As a model experiment, an investigation was made with the oxidation of methane. As all catalysts with various Fe contents supported on χ- Al 2 O 3 with various Fe contents had higher specific surface areas than those supported on γ- Al 2 O 3, α- Fe 2 O 3/χ- Al 2 O 3 catalyst has higher catalytic activities than α- Fe 2 O 3/γ- Al 2 O 3 catalyst. From SEM-EDS analyses, it is concluded that in α- Fe 2 O 3/χ- Al 2 O 3 catalyst, α- Fe 2 O 3 exists mainly on the surface of the support, because of flatness of the surface of χ- Al 2 O 3. On the other hand, in the case of α- Fe 2 O 3/γ- Al 2 O 3 catalyst, as the surface of support, γ- Al 2 O 3, is uneven, α- Fe 2 O 3 do not partially exist on the surface but in the pores.

Pressure die casting conditions for investigating chemical composition effect of melts on gas volume in die castings.

The characteristics of crucibles made of graphite, mullite, alumina, and stainless steel (SUS 27) were examined for the purpose of retaining a molten aluminum sample in the extraction tube of gas measuring apparatus. The gas volume extracted by these crucibles or blank gas volume was measured, and hydrogen contents of aluminum samples were also measured from vacuum fusion extraction method by using these crucibles.The results showed that a crucible made of SUS 27 was more excellent in characteristics than those of other ones. Then, the following tests were conducted by using the SUS 27 crucible.(1) Reliability of measured values of hydrogen in aluminum obtained by vacuum fusion extraction method.(2) Distribution of hydrogen in the aluminum castings poured into the Ransley's chill mold.

Table 1 Chemical composition of specimen (wt%).