VIBRATION-DAMPED PRECISION CAST ALUMINUM ALLOY AUTOMOTIVE MEMBER FOR A VEHICLE POWERTRAIN AND METHOD OF MANUFACTURING THE SAME
A vibration-damped precision cast aluminum alloy automotive member for a vehicle powertrain and a method of its manufacture are disclosed. The vibration-damped precision cast aluminum alloy automotive member includes an internally disposed aluminum or aluminum alloy insert. An exterior surface of the insert, which includes an exposed oxide film, establishes a non-bonded interface with an interior surface of the automotive powertrain member. This non-bonded interface damps vibration propagation through the automotive powertrain member by experiencing frictional contacting movement when the automotive powertrain member is vibrationally excited.
1 . A method of making a vibration-damped precision cast aluminum alloy automotive member for a vehicle powertrain, the method comprising:
obtaining an insert, which is constructed of aluminum or an aluminum alloy, that comprises an oxide film exposed at an exterior surface of the insert, the oxide film having a thickness that ranges from about 1 nm to about 20 μm; and
solidifying a molten aluminum alloy charge around the insert in a die cavity defined by a re-useable die and configured to resemble an automotive powertrain member, the insert being positioned in the die cavity at a predetermined site, and the molten aluminum alloy charge being solidified into a vibration-damped automotive powertrain member that includes a non-bonded interface between an interior surface of the automotive powertrain member and the oxide film at the exterior surface of the insert so that frictional contacting movement transpires between the interior surface and the oxide film when the automotive powertrain member is subjected to vibratory excitement;
wherein the vibration-damped automotive powertrain member comprises a structural wall that includes an inner surface and an outer surface, the structural wall having a thickness between the inner surface and the outer surface that ranges from about 2 mm to about 20 mm, and wherein the aluminum or aluminum alloy insert has a thickness, measured in a direction consistent with the thickness of the structural wall from the inner surface to the outer surface, that ranges from about 10% to about 70% of the thickness of the structural wall.
2 . The method set forth in claim 1 , wherein obtaining the insert comprises forming the oxide film at the exterior surface of the insert by exposing a bare aluminum or aluminum alloy surface of the insert to oxygen to promote self-passivation.
3 . The method set forth in claim 1 , wherein obtaining the insert comprises forming the oxide film at the exterior surface of the insert by anodizing either a bare or passivated aluminum or aluminum alloy surface of the insert.
4 . (canceled)
5 . The method set forth in claim 1 , further comprising:
introducing the molten aluminum alloy charge into the die cavity and into contact with the exterior surface of the insert under an applied elevated pressure.
6 . The method set forth in claim 5 , wherein the elevated pressure applied to the molten aluminum alloy charge in the die cavity is in the range of about 1,500 psi to about 30,500 psi.
7 . The method set forth in clam 1 , wherein the die cavity is configured to resemble a transmission housing, an electric motor housing, a differential housing, or an invertor housing.
8 . A method of making a vibration-damped precision cast aluminum alloy automotive member for a vehicle powertrain, the method comprising:
forming an oxide film at an exterior surface of an aluminum or an aluminum alloy insert by anodizing either a bare or passivated surface of the insert, the oxide film having a thickness that ranges from about 1 nm to about 20 μm;
locating the insert in a die cavity defined by a re-useable precision casting die, the die cavity being shaped to resemble an automotive member for a vehicle powertrain;
introducing a molten aluminum alloy charge into the die cavity and into contact with the exterior surface of the insert under an applied elevated pressure; and
solidifying the molten aluminum alloy charge over the exterior surface of the insert to form the vibration-damped automotive powertrain member having a non-bonded interface between an interior surface of the automotive powertain member and the oxide film at the exterior surface of the insert so that frictional contacting movement transpires between the interior surface and the oxide film when the automotive powertain member is subjected to vibratory excitement.
9 - 11 . (canceled)
12 . The method set forth in claim 8 , wherein the elevated pressure applied to the molten aluminum alloy charge in the die cavity is in the range of about 1,500 psi to about 30,500 psi.
13 . The method set forth in claim 8 , wherein the automotive powertrain member is a housing that includes a structural wall having an inner surface and an outer surface, the structural wall having a thickness between the inner and outer surfaces from about 2 mm to about 20 mm, and wherein the aluminum or aluminum alloy insert is disposed within the structural wall.
14 . The method set forth in claim 13 , wherein the aluminum or aluminum alloy insert is disposed in the structural wall between the inner and outer surfaces, and wherein the aluminum or aluminum alloy insert has a thickness, measured in a direction consistent with the thickness of the structural wall from the inner surface to the outer surface, that is between about 10% and about 70% of the thickness of the structural wall.
15 . A vibration-damped precision cast aluminum alloy automotive member for a vehicle powertrain comprising:
a precision cast aluminum alloy automotive member for a vehicle powertrain constructed of aluminum or an aluminum alloy that includes an interior surface; and
an insert disposed within the precision cast aluminum alloy automotive member, the insert being constructed of aluminum or an aluminum alloy and comprising an exterior surface that forms a non-bonded interface with the interior surface of the automotive member, the exterior surface of the aluminum insert having an oxide film exposed at the non-bonded interface of the exterior surface of the insert and the interior surface of the automotive member.
16 . The vibration-damped precision cast aluminum alloy automotive member for a vehicle powertrain set forth in claim 15 , wherein the oxide film has a thickness between about 1 nm and about 20 μm.
17 . The vibration-damped precision cast aluminum alloy automotive member for a vehicle powertrain set forth in claim 15 , wherein the automotive powertrain member is a housing that includes a structural wall having an inner surface and an outer surface, the structural wall having a thickness between the inner and outer surfaces from about 2 mm to about 20 mm, and wherein the aluminum or aluminum alloy insert is disposed within the structural wall.
18 . The vibration-damped precision cast aluminum alloy automotive member for a vehicle powertrain set forth in claim 17 , wherein the automotive member for a vehicle powertrain is a transmission housing, an electric motor housing, a differential housing, or an invertor housing.
19 . The vibration-damped precision cast aluminum alloy automotive member for a vehicle powertrain set forth in claim 17 , wherein the aluminum or aluminum alloy insert is disposed in the structural wall between the inner and outer surfaces, and wherein the aluminum or aluminum alloy insert has a thickness, measured in a direction consistent with the thickness of the structural wall from the inner surface to the outer surface, that is between about 10% to about 70% of the thickness of the structural wall.
20 . The vibration-damped precision cast aluminum alloy automotive member for a vehicle powertrain set forth in claim 15 , wherein the aluminum or aluminum alloy insert is not covered with a coating that comprises refractory particles.
21 . The method set forth in claim 1 , wherein the aluminum or aluminum alloy insert is not covered with a coating that comprises refractory particles.
22 . The method set forth in claim 8 , wherein the aluminum or aluminum alloy insert is not covered with a coating that comprises refractory particles.
23 . The method set forth in claim 8 , wherein the anodizing comprises:
providing an aqueous electrolyte solution;
immersing the aluminum or aluminum alloy insert into the aqueous electrolyte solution and connecting the aluminum or aluminum alloy insert to a power supply as an anode; and
immersing an electrically conductive material, which is inert to the aqueous electrolyte solution, into the aqueous electrolyte solution and connecting the electrically conductive material to the power supply as a cathode.
24 . The method set forth in claim 8 , wherein the anodizing is performed so that the oxide film has a crystalline microstructure.