Patent ID: 12203188

DETAILED DESCRIPTION

The part assembly and method of manufacture described herein concern an aluminium and magnesium coated part assembly and method of manufacture.

Embodiments of the present invention may tackle one or more of the problems previously mentioned by subjecting the aluminium part, the coated magnesium part and the bond to an electrophoresis coating process to coat the aluminium part in a second coating. In this way, it is possible to provide a simpler manufacturing process and a corrosion resistant part assembly bond.

FIG.1schematically illustrates an exemplary embodiment of a part assembly of the present invention.FIG.1aschematically illustrates a perspective view of the part assembly of the embodiment.FIG.1bschematically illustrates a side view of the part assembly of the embodiment including a section A-A.FIG.1cschematically illustrates a cross-sectional view through the section A-A ofFIG.1bof the part assembly of the embodiment.

FIG.1is illustrative and not to scale. It may be appreciated that the relative dimensions and shapes of the components may be varied within the scope of the invention.

FIG.1cillustrates a part assembly100comprising an aluminium part101and a magnesium part102. The aluminium part101may be an aluminium-based part. In other words, the aluminium-based part may comprise an aluminium alloy. Preferably, the aluminium alloy is a Superformed5083aluminium alloy. The magnesium part102may be a magnesium-based part. In other words, the magnesium-based part may comprise a magnesium alloy. Preferably, the magnesium alloy is a AZ31B magnesium alloy.

The magnesium part102may be coated in a first coating104. The first coating104may comprise a powder coating. The first coating104may be applied by spraying. Alternatively, the first coating104may be applied by other means, such as dipping the magnesium part102in the first coating104material. By applying the powder coating over the magnesium part this may provide a smooth and even finish as described herein. The first coating104may comprise an epoxy powder coat material. This epoxy powder coat material may provide corrosion resistance to protect the magnesium part against oxidisation.

Additionally, the magnesium part102may be coated in a pre-treatment coating prior to applying the first coating102. The pre-treatment coating may aid the adhesion between the magnesium part102and the first coating104. The pre-treatment coating may further improve the corrosion resistance of the first coating104.

Additionally, the first coating104may comprise more than one layer. For example, a first layer of the first coating104may be applied to the magnesium part102, or to the pre-treatment coating on the magnesium part102. A second layer of the first coating104may be applied to the first layer of the first coating104. The first layer of the first coating104may be cured before the second layer of the first coating104is applied. Where the first coating104comprises more than two layers the curing and applying process may be repeated for each layer.

As shown inFIG.1c, preferably, the first coating104may comprise a generally constant thickness around the magnesium part102. By providing a constant thickness of the first coating104this may reduce the likelihood of weak spots through which corrosion may penetrate. Preferably, the first coating104may comprise a smooth outer surface as shown inFIGS.1aand1c. By providing a smooth outer surface this may reduce the likelihood of external components catching and damaging the first coating104which may create a hole through which corrosion may penetrate.

Preferably, the first coating104material thickness is greater than 100 μm. By providing this minimum thickness of the first coating104this may increase the strength of the first coating104and reduce the likelihood of external components damaging the first coating104which may create a hole through which corrosion may penetrate.

Additionally, the electrophoresis coating process, described herein, may cause the first coating104to corrode, deteriorate or delaminate. By providing this minimum thickness of the first coating104this may also enable the first coating104to retain structure during the electrophoresis coating process.

Coating the magnesium part102in a first coating104may provide a coated magnesium part114.

As shown inFIG.1c, the part assembly100may comprise a bond103. The bond103may provide a securing means for securing the aluminium part101to the coated magnesium part114.

The bond103material may comprise structural epoxy adhesive. This structural epoxy adhesive material may provide a high mechanical strength bond between the aluminium part101and the magnesium part102. This structural epoxy adhesive material may also reduce the likelihood of a galvanic reaction between the aluminium part101and the magnesium part102.

As shown inFIG.1c, a first mating surface107of the bond103is secured to a mating surface106of the aluminium part101. Preferably, the first mating surface107of the bond103is in direct contact with the aluminium part101. The mating surface106of the aluminium part101may be provided on the surface facing the magnesium part102, as shown inFIG.1c. The bond103may cover the entire mating surface106of the aluminium part101. In this way, the bond103may provide the maximum securing strength for securing the aluminium part101to the bond103and may reduce the likelihood of corrosion penetrating to the aluminium part through gaps in the bond103.

As shown inFIG.1c, a second mating surface108of the bond103is secured to a mating surface109of the coated magnesium part114. Preferably, the second mating surface108of the bond103is in direct contact with the first coating104. The mating surface109of the coated magnesium part114may be provided on the surface facing the aluminium part101, as shown inFIG.1c. The bond103may cover the entire mating surface109of the coated magnesium part114. In this way, the bond103may provide the maximum securing strength for securing coated magnesium part114to the bond103and may reduce the likelihood of corrosion penetrating to the coated magnesium part114through gaps in the bond103.

In an alternative embodiment, the first coating104may be arranged to comprise an opening through which the bond103may make direct contact with the magnesium part102. This arrangement may provide a secure contact between the bond103and the magnesium part102.

The bond103may comprise a rectangular cross-sectional structure as illustrated inFIG.1c. Alternatively, the bond103may comprise a thin veneer or coating applied to the mating surfaces106,109of the aluminium part101and magnesium part102. In either event, as mentioned herein, preferably, the bond103may cover the entire mating surface106of the aluminium part101and the entire mating surface109of the coated magnesium part114.

The aluminium part101, the coated magnesium part114and the bond103may be subjected to an electrophoresis coating process so that the aluminium part101is coated in a second coating105. Preferably, as shown inFIGS.1aand1c, the second coating105is arranged to cover the entire surface of the aluminium part101except for the mating surface106. This arrangement may be a result of the electrophoresis coating process as the aluminium part101and the bond103may be subjected to the electrophoresis coating process together. This arrangement may enable the bond103to be in direct contact with the aluminium part101which may provide a secure contact.

As shown inFIGS.1aand1c, preferably, the second coating105is arranged to extend continuously over the aluminium part101up to the joint between the aluminium part101and the bond103. This may provide a seal between the aluminium part101and the bond103which may reduce the likelihood of corrosion penetrating to the aluminium part101through the joint between the aluminium part101and the bond103.

Coating the aluminium part101in a second coating105may provide a coated aluminium part115.

Preferably, as shown inFIG.1c, the coated magnesium part114is not coated in the second coating105. This may be a result of the electrophoresis coating process as the first coating104may provide an insulating layer between the second coating105and the magnesium part102such that the electrophoresis coating process does not adhere the second coating105to the surface of the first coating104.

The bond103may not be coated in the second coating105. This may be because the bond103material is not electrically conductive.

The second coating105material may comprise a cathodic epoxy coating, such as a black cathodic epoxy coating. This cathodic epoxy coating material may provide high corrosion resistance to the aluminium part102.

As shown inFIG.1c, preferably, the second coating105comprises a generally constant thickness around the aluminium part101. By providing a constant thickness of the second coating105this may reduce the likelihood of weak spots through which corrosion may penetrate. Preferably, the second coating105may comprise a smooth outer surface as shown inFIGS.1aand1c. By providing a smooth outer surface this may reduce the likelihood of external components catching and damaging the second coating105which may create a hole through which corrosion may penetrate.

Preferably, the second coating105material thickness is greater than 20 μm. By providing this minimum thickness of the second coating105this may increase the strength of the second coating105and reduce the likelihood of external components damaging the second coating105which may create a hole through which corrosion may penetrate.

Preferably, as shown inFIG.1c, a first mating edge110of the coated aluminium part115and a first mating edge112of the coated magnesium part114are arranged to be flush. Additionally, a second mating edge111of the coated aluminium part115and a second mating edge113of the coated magnesium part114are arranged to be flush. In other words, the corresponding edges (110and112,111and113) are aligned so that there is not a step or ridge provided on the surface of the part assembly100. This may provide a smooth outer surface which may reduce the likelihood of external components catching and damaging the first coating104and the second coating105which may create a hole through which corrosion may penetrate.

In the embodiment shown inFIG.1c, the bond103comprises a rectangular cross-sectional structure with a visible thickness. In this arrangement, the corresponding edges (110and112,111and113) are aligned but are spaced apart by the bond103. Alternatively, the bond103may comprise a thin veneer or coating which may not be clearly visible. In this alternative arrangement, the corresponding edges (110and112,111and113) may be aligned and may be close. In other words, the thickness of the bond103may be varied. In either arrangement, it is preferable that the edges are aligned so that the bonding is flush.

The first mating edges110,112may be provided on the upper edge (as shown inFIG.1c) of the mating surfaces106,109of the coated aluminium and coated magnesium parts115,114. The second mating edges111,113may be provided on the lower edge (as shown inFIG.1c) of the mating surfaces106,109of the coated aluminium and coated magnesium parts115,114. In this embodiment, the edges110,111,112,113are provided by the second coating105and the first coating104.

As shown inFIG.1c, the edges of the aluminium part101and the magnesium part102may also be arranged to be flush. As the aluminium part101and the magnesium part102are internal of the part assembly100it may not be essential for the parts to be flush. However, if the first coating104and the second coating105are sufficiently thin such that they are thinner than the difference between the position of the edges of the aluminium part101and the magnesium part102then this may provide a step or ridge in the part assembly100. Therefore, it is preferable for the edges of the aluminium part101and the magnesium part102to be generally flush.

In an alternative embodiment, the aluminium part101and the magnesium part102may be arranged in corner, or similar, joint. In this alternative embodiment, the edges110,111,112,113may not be flush and instead may provide a corner or angle.

FIG.1shows part assembly100. The part assembly100illustrated inFIG.1comprises a planar structure. In other words, the height and width of the part assembly100is significantly wider that the depth of the part assembly100. The part assembly100may also comprise a range of structures depending on the design requirements, such as two non-planar parts joined or a corner joint.

FIG.2illustrates an exemplary embodiment of a vehicle comprising a panel comprising the part assembly of the embodiment.

The part assembly100may be used in a panel201, as shown inFIG.2. The panel201may comprise one part assembly, or a plurality of part assemblies100depending on the design requirements for the panel201. The part assembly100may also be used in a range of other applications, for example using the non-planar structure parts described herein.

The panel201may be used on a vehicle202, as shown inFIG.2. In particular, the vehicle202may be, for example, an automobile, train or aircraft. If the panel201is used on an automobile, the panel201may be a door panel.

The panel201may also be used in non-vehicle applications such as in building construction.

FIGS.3a-cschematically illustrate an exemplary embodiment of a method of manufacture of the present invention.FIG.3aschematically illustrates a perspective view of the method of manufacture of the embodiment.FIG.3bschematically illustrates a side view of the method of manufacture of the embodiment including sections B-B, C-C and D-D.FIG.3cschematically illustrates a cross-sectional view through the sections B-B, C-C and D-D ofFIG.3bof the method of manufacture of the embodiment.

FIGS.3a-cillustrate a method of manufacture300corresponding to the part assembly100described herein. It may be appreciated that the method of manufacture300may be used to manufacture a variety of alternative embodiments of the part assembly100within the scope of the invention.

As shown inFIGS.3a-c, an aluminium part101, a bond103, and a coated magnesium114part are provided. The aluminium part101may be provided as described herein in relation to the part assembly100. The bond103may be provided as described herein in relation to the part assembly100. The coated magnesium part114may be provided as described herein in relation to the part assembly100.

Before the coated magnesium part114is provided, a magnesium part102may be coated in a first coating104, as described herein in relation to the part assembly100, to form the coated magnesium part114. The coating of the magnesium part114is not illustrated inFIGS.3a-c. The coating of the magnesium part102may be carried as part of the manufacturing process300. Alternatively, the coating of the magnesium part102may be carried out before the manufacturing process300or before the manufacturing process300such that the coated magnesium part114is provided for the manufacturing process300.

As shown inFIGS.3a-c, the aluminium part101is secured to the coated magnesium part114using a bond103. The bond103may be arranged as described herein in relation to the part assembly100. The securing of the aluminium part101to the coated magnesium part114is illustrated inFIGS.3a-c. The securing of the aluminium part101to the coated magnesium part114may be carried as part of the manufacturing process300. Alternatively, the securing of the aluminium part101to the coated magnesium part114may be carried out before the manufacturing process300or before the manufacturing process300, such that the aluminium part101secured to the coated magnesium part114is provided for the manufacturing process300.

The aluminium part101, the coated magnesium part114and the bond103are subjected to an electrophoresis coating process. As shown inFIGS.3a-c, the electrophoresis coating process coats the aluminium part101in a second coating105. Preferably, as shown inFIGS.3aand3c, the second coating105covers the entire surface of the aluminium part101except for the mating surface106. This arrangement may result from the aluminium part101and the bond103, which are secured at their corresponding mating surfaces106,107, both being subjected to the electrophoresis coating process together. In this way, the surfaces106,107are not exposed to the electrophoresis coating process.

Preferably, subjecting aluminium part101, the coated magnesium part114and the bond103to an electrophoresis coating process does not coat the coated magnesium part114in the second coating105. Preferably the first coating104may provide an insulating layer between the second coating105and the magnesium part102such that the electrophoresis coating process does not adhere the second coating105to the surface of the first coating104.

Additionally, by subjecting aluminium part101, the coated magnesium part114and the bond103to an electrophoresis coating process does not coat the bond103in the second coating105. This may be because the bond103material is not electrically conductive. Preferably, the bond103comprises a structural epoxy adhesive material, as described herein.

Preferably the first coating104has a thickness of greater than 100 μm. The electrophoresis coating process may cause the first coating104to deteriorate or delaminate. By providing a first coating104of sufficient thickness this may enable the first coating104to retain structure and not deteriorate or delaminate during the electrophoresis coating process. Preferably, after the electrophoresis coating process, the magnesium coated part114may survive a 720 hr Natural Salt Spray (NNS) test according to ASTM B117.

Before carrying out the electrophoresis coating process the aluminium part101, the coated magnesium part114and the bond103may be cleaned. Additionally, before carrying out the electrophoresis coating process the aluminium part101, the coated magnesium part114and the bond103may be coated in a conversion coating, such as an inorganic phosphate coating.

The electrophoresis coating process may comprise submerging the aluminium part101, the coated magnesium part114and the bond103into a coating solution. The coating solution may comprise the black cathodic epoxy material in a fluid state.

The electrophoresis coating process may comprise applying a voltage to the aluminium part101, the coated magnesium part114and the bond103in the coating solution. The voltage may be applied through an electrode to the aluminium part101, such that the aluminium part101, the coated magnesium part114and the bond103may provide an electrode. Alternatively, fasteners may be used to apply the voltage to the coated magnesium part102. The coating solution may be oppositely charged to the aluminium part101, the coated magnesium part114and the bond103providing the electrode such that particles in the coating solution may be attracted to the aluminium part101. The voltage and/or the pH of the coating solution may be varied such that the rate of attraction of the particles in the coating solution may be varied. In this way, the application rate of the second coating105may be varied such that the thickness of the second coating105may be controlled. Alternatively, or additionally, the duration of the electrophoresis coating process may be varied such that the thickness of the second coating105may be controlled.

The electrophoresis coating process may comprise removing the aluminium part101, the coated magnesium part114and the bond103from the coating solution. After the aluminium part101, the coated magnesium part114and the bond103are removed from the coating solution the aluminium part101, the coated magnesium part114and the bond103may be rinsed. The rinsing may clean and remove any residual coating solution from the aluminium part101, the coated magnesium part114and the bond103.

The electrophoresis coating process may comprise subjecting the aluminium part101, the coated magnesium part114and the bond103to a temperature increase so as to cure the coating solution into the second coating105. The temperature increase may comprise heating the aluminium part101, the coated magnesium part114and the bond103to over 180° C. The aluminium part101, the coated magnesium part114and the bond103may be cooled to harden and cure the second coating105.

As described herein, the part assembly and method of manufacture may be practically applied to other implementations, such as panels and other structures, on different types of vehicles or non-vehicle applications.

The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims. The applicant indicates that aspects of the present invention may consist of any such individual feature or combination of features. In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention.