Kabushiki Kaisha Toyoda Jidoshokki Seisakusho

Toyota Jidosha Kabushiki Kaisha

Other

Hidetoshi Hirai

Tomohito Ito

Fukuo Gomi

Renichi Isomura

Atsuo Tanaka

Tadashi Dohnomoto

Masahiro Kubo

Senichi Masuda

Takashi Yoshida

Mitsuyoshi Shirotani

A process for producing fiber aggregate which comprises the steps of coating a conductive material which is insoluble in a dielectric fluid on the surface of fibers; dispersing the fibers into the dielectric fluid to obtain a fiber suspended fluid; introducing the fiber suspended fluid into an electric field which is generated in a space between a positive electrode and a negative electrode, whereby causing individual fibers to electrostatically and one-dimensionally orient; and aggregating the oriented fibers. The conductive material contributes to charge-transfer, and it causes the fibers in the electric filed to orient stably.

Process for producing fiber aggregate

An apparatus for producing annular fiber aggregate includes: a container including an inner cylinder and an outer cylinder disposed concentrically, whereby forming an upright cylindrical space between the inner cylinder and the outer cylinder; at least a pair of positive electrode and negative electrode disposed by turns and buried in the wall of the outer cylinder, parallely with respect to the axis of the upright cylindrical space; a filter member disposed at the lower portion of the upright cylindrical space; and a voltage applicator connected to the positive electrodes and the negative electrodes. Since the apparatus has the positive and negative electrodes buried in the wall of the outer cylinder, the fibers are hardly disturbed and lifted by the positive and negative electrodes even when the positive and negative electrodes are rotated relatively around the axis of the upright cylindrical space. Thus, a fiber aggregate can be obtained in which the fibers are oriented in the peripheral tangent direction uniformly and favorably, and the strength thereof in the direction perpendicular to the peripheral tangent direction has been further enhanced.

Apparatus for producing annular fiber aggregate

The present invention relates to a process for producing fiber aggregate which includes an orientation step of placing the dielectric fluid containing fibers in the form of short fiber, whisker, or a mixture thereof dispersed therein in a space between a pair of electrodes across which an AC voltage is applied, whereby causing individual fibers in the dielectric fluid to electrostatically orient, with one end pointing to one of electrodes and the other end pointing to the other electrode; and an aggregating step of aggregating the electrostatically oriented fibers while keeping the oriented step, whereby producing fiber aggregate in which the fibers are substantially one-dimensionally oriented.

A fiber aggregate in which many of the fibers are oriented in the tangent direction of the circumference satisfactorily can be produced by a process and an apparatus according to the present invention. The best feature of the present invention is the following arrangement for a plurality of electrodes used in a process and an apparatus according to the present invention. Vertically extending foil, net or needle-shaped electrodes for orienting the fibers electrostatically are disposed alternately along the circumference of the vertically cylindrical space so as to divide the vertically cylindrical space into equal parts. In addition to this arrangement, the plurality of electrodes may be rotated as well as moved vertically in order not to disturb the fiber aggregation. A fiber aggregate obtained by the present invention has an improved strength and anti-thermal properties.

Apparatus for producing a fiber aggregate

The feature of the present invention is that a fiber mixture of silicon carbide or silicon nitride whiskers and alumina or alumina-silica short fibers with 1 to 45 volume percent of the short fibers in relation to the total volume of the whiskers and short fibers is used in the following steps for producing a fiber aggregate: a dispersion step of dispersing whiskers and short fibers into a dielectric fluid; an orientation step of placing the dielectric fluid containing the fibers dispersed therein in a space between a positive electrode and a negative electrode across which a high voltage is applied, whereby causing individual fibers in the dielectric fluid to electrostatically orient, with one end pointing to the positive electrode and the other end pointing to the negative electrode; and an aggregating step of aggregating the electrostatically oriented fibers while keeping the oriented step. The fiber mixture is used in order to grow the bridgings of whiskers around the short fibers as cores. Thus the fiber sedimentation is accelerated by densely bridged fibers while maintaining a satifactory orientation. Hence a whisker aggregate with a larger fiber volume ratio Vf can be formed in a shorter period of time.

Process for producing a fiber aggregate

A composite material is made from reinforcing fiber material embedded in a matrix of metal. The matrix metal is a light metal such as aluminum alloy or magnesium alloy. The reinforcing fiber material is a mixture of potassium titanate whiskers and a short fiber material, which is one or a mixture of: silicon carbide whiskers, silicon nitride whiskers, alumina short fibers, crystalline alumina-silica short fibers, and amorphous alumina-silica short fibers. The overall volume proportion of the reinforcing fiber material in the composite material is between approximately 5% and approximately 50%, and more desirably may be between approximately 5% and approximately 40%, and even more desirably may be between approximately 10% and approximately 40%. And the relative volume proportion of the potassium titanate whiskers in the reinforcing fiber material is from about 10% to about 80%, and more desirably may be between approximately 10% and approximately 70%, and even more desirably may be between approximately 20% and approximately 60%.

Composite material with light matrix metal and with reinforcing fiber

A composite material is made from alumina-silica type short fibers embedded in a matrix of metal. The matrix metal is an alloy consisting essentially of from approximately 2% to approximately 6% of copper, from approximately 0.5% to approximately 3.5% of magnesium, and remainder substantially aluminum. The short fibers have a composition of from about 35% to about 80% of Al.sub.2 O.sub.3 and from about 65% to about 20% of SiO.sub.2 with less than about 10% of other included constituents, and may be either amorphous or crystalline, in the latter case optionally containing a proportion of the mullite crystalline form. The fiber volume proportion of the alumina-silica type short fibers is between approximately 5% and approximately 50%, and may more desirably be between approximately 5% and approximately 40%. If the alumina-silica short fibers are formed from amorphous alumina-silica material, the magnesium content of the aluminum alloy matrix metal may desirably be between approximately 0.5% and approximately 3%. And, in the desirable case that the fiber volume proportion of the alumina-silica type short fibers is between approximately 30% and approximately 40%, then the copper content of the aluminum alloy matrix metal is desired to be between approximately 2% and approximately 5.5%.

Composite material including alumina-silica short fiber reinforcing

A composite material is made from silicon carbide and/or silicon nitride short fibers embedded in a matrix of metal. The metal is an alloy consisting essentially of between approximately 2% to approximately 6% of copper, between approximately 0.5% to approximately 3% of silicon, and remainder substantially aluminum. The short fibers may be all silicon carbide short fibers, or may be all silicon nitride short fibers, or may be a mixture of silicon carbide and silicon nitride short fibers. The fiber volume proportion of the silicon carbide and/or silicon nitride short fibers may desirably be between approximately 5% and approximately 50%, and may more desirably be between approximately 5% and approximately 40%.

Growing community of inventors

Kariya, Japan

Hidetoshi Hirai