|Title of Invention||
PROCESS FOR THE FABRICATION OF FLYASH REINFORCED METAL COMPOSITES
|Abstract||Disclosed herein is a process for the fabrication of metal composites by casting route wherein fly-ash is used as the reinforment material. The metal can be selected form Magnesium, Aluminium and their alloys.|
This invention relates to a process for the fabrication of flyash reinforced metallic composites.
1. FIELD OF TECHNOLOGY:
This invention in general relates to the field of materials technology. Further, this invention relates to the field of material processing. More particularly this invention relates to a process for the fabrication of metallic-flyash reinforced composites by casting route.
2. PRESENT STATE OF ART:
Composite materials have become technologically important. Ceramic particle reinforced Magnesium and Mg alloy matrix composites are considered to be candidate materials in aerospace applications because of their low density and superior stiffhess.
In general, MMCs (Metal Matrix Composites) based on Mg and its alloys reinforced with ceramic particles such as SiC have been produced. In all these composites expensive reinforcements are utilised. Hence, there is a need to substitute these reinforcements with a easily available and inexpensive reinforcements.
The following specifications describe in details the various aspects of prior art technology and short comings in the choice of reinforcement currently in use in the fabrication of metal based composites. The metal can be selected from Magnesium, Aluminium and their alloys, and in particular Magnesium. The invention proposes a solution to overcome the problem associated with prior art systems. This is reflected in the objective of the invention.
Existing process rely on ceramic reinforcements which are expensive. Hence, there is an imperative need to find a substitute for these reinforcements and also develop a process to fabricate metal based composites using inexpensive reinforcements.
The primary objective of the invention to substitute the expensive reinforcement by flyash which is also an industrial waste.
Another objective is to develop a process to fabricate flyash-reinforced composite using conventional casting route.
Another objective of the invention is to increase the elastic modulus and strength of Mg by reinforcing with flyash.
Another objective of the invention is to produce a flyash reinforced Mg composite having low coefficient of thermal expansion.
Further aspects of the invention will be clear from the following description:
Fabrication of Metal-flyash reinforced composites by casting route, the process comprises following steps.
a. Melting of a metal, such as aluminium, magnesium or their alloys,
b. Incorporation of preheated flyash particles into the molten metal, and
c. Homogeneous mixing of aforesaid materials, followed by the formation of the
composite by known methods.
The nature of the invention and the manner in which it is to be performed is clearly described in the following description, with reference to magnesium. It may be noted that the present invention is also applicable to other metals, including magnesium alloys and aluminium and its alloys.
Magnesium 10 vol% flyash composite was processed by melt stir technique. The matrix material was 99% pure magnesium and flyash particle with 15 ^im average size. Steps involved and the procedure employed for the fabrication of the composites are as follows. The melting was carried out using a resistance-heating furnace of 5KW. Stainless crucible with a capacity to hold 5 Kg of metal was used for melting Magnesium and subsequent processing of composites. Magnesium ingot weighing about 2 Kg was fully wrapped with aluminium foil and charged into the stainless steel crucible. During melting the furnace was purged with SF6H-Ar This is done to prevent the oxidation and burning of the Magnesium melt. Temperature was monitored and controlled closely during the
addition of flyash particles. The, melt was stirred to create a vortex. Preheated flyash particles were added to the vortex formed by the rotating stainless steel impeller.
The composite melt was poured into cast iron cylindrical mould of 65mm diameter and 220 mm height.
DESCRIPTION OF THE DRAWINGS:
Fig. 1 illustrates the SEM micrograph of flyash particles; and
Fig. 2 illustrates the Optical micrograph of the cast Mg-flyash composite prepared
according to the present invention.
4. PROPOSED SOLUTION:
A method is proposed to process flyash reinforced Magnesium metal matrix composites. The method involves procedure for melting of Magnesium and subsequent incorporation of preheated flyash particles into the molten Magnesium and their mixing. Composites thus processed posses superior stiffness.
It is to be understood that the description clearly describes various aspects of the invention and construded such that the description is in no way limiting the scope of the invention. It is further understood that within the scope of the invention various modifications are permissible. The statement of claims is described in the following description.
5. ADVANTAGES OF THE INVENTION:
UTS i.e. Ultimate Tensile Strength and compression strength of composites thus prepared are at least 10% more than the unreinforced Magnesium Hardness and Young's modulus are higher by more than 50% and 30% respectively compared to pure Magnesium.
The process developed can easily be adapted in Foundries.
1. A process for the fabrication of Metal-flyash composites by casting route,
(a) Melting of a metal such as Magnesium, Aluminium and their alloys,
(b) Incorporating the preheated flyash particles into the molten metal; and
(c) Mixing the aforesaid materials homogeneously, followed by the formation of the composite by known methods.
2. A process as claimed in claim 1, wherein the metal used is magnesium.
3. A process as claimed in claim 2, wherein the melting of magnesium is carried out at a temperature of 700^ C
4. A process as claimed in claim 2 or claim 3, wherein the magnesium 10 vol% flyash composite is processed by melt stir technique.
5. A process as claimed in any one of claims 2 to 4, wherein the matrix material is
99% pure magnesium and flyash particle of 15^m average size.
6. A process for the fabrication of metal-flyash composites by casting route substantially as hereinbefore described and illustrated.
|Indian Patent Application Number||259/MAS/2003|
|PG Journal Number||20/2006|
|Date of Filing||26-Mar-2003|
|Name of Patentee||M/S. INDIAN INSTITUTE OF SCIENCE|
|Applicant Address||BANGALORE - 560 012|
|PCT International Classification Number||C22C 21/00|
|PCT International Application Number||N/A|
|PCT International Filing date|