Corrosion-resistant permanent magnet for an intravascular blood pump
This invention is directed to a corrosion-resistant permanent magnet, to a method for producing a corrosion-resistant permanent magnet, and to an intravascular blood pump comprising the magnet. The magnet is surrounded by a composite coating, the composite coating comprising, in the order recited, a first metal oxide layer, a metal layer, a second metal oxide layer, a linker layer, and a layer formed from poly(2-chloro-p-xylylene). In an alternative embodiment, a further metal layer and, optionally, a further metal oxide layer may be provided between the second metal oxide layer and the linker layer. In a further alternative embodiment, the metal layer may be omitted, and a further layer structure comprising at least one metal oxide layer, a linker layer, and a layer formed from poly(2-chloro-p-xylylene) may be provided instead.
1 . A corrosion-resistant permanent magnet comprising a magnet body and a composite coating provided on and covering surfaces of the magnet body, the composite coating comprising, in the order recited,
a first metal oxide layer in physical contact with the magnet body, wherein a thickness of the first metal oxide layer is in a range from 80 nm to 120 nm;
a metal layer;
a second metal oxide layer;
a linker layer; and
a layer formed from poly(2-chloro-p-xylylene).
2 . The corrosion-resistant permanent magnet of claim 1 , wherein the magnet body is a rare earth metal iron boron permanent magnet.
3 . The corrosion-resistant permanent magnet of claim 2 , wherein the magnet body is a sintered magnet body having Nd 2 Fe 14 B crystals and a neodymium iron boron material surrounding the Nd 2 Fe 14 B crystals, said neodymium iron boron material being richer in neodymium than the Nd 2 Fe 14 B crystals.
4 . The corrosion-resistant permanent magnet of claim 1 , wherein the metal of the metal layer is aluminum or titanium or an alloy of aluminum or titanium.
5 . The corrosion-resistant permanent magnet of claim 1 , wherein the oxide of the first metal oxide layer is Al 2 O 3 or TiO 2 or a mixed oxide of Al 2 O 3 and TiO 2 .
6 . The corrosion-resistant permanent magnet of claim 1 , wherein the oxide of the second metal oxide layer is Al 2 O 3 or TiO 2 or a mixed oxide of Al 2 O 3 and TiO 2 .
7 . The corrosion-resistant permanent magnet of claim 1 , comprising a further metal layer and, optionally, a further metal oxide layer between the second metal oxide layer and the linker layer, wherein
the metal layer is in physical contact with the first metal oxide layer,
the second metal oxide layer is in physical contact with the metal layer,
the further metal layer is in physical contact with the second metal oxide layer,
the further metal oxide layer, if present, is in physical contact with the further metal layer,
the linker layer is in physical contact with the further metal layer or, if present, the further metal oxide layer, and
the layer formed from poly(2-chloro-p-xylylene) is in physical contact with the linker layer.
8 . The corrosion-resistant permanent magnet of claim 7 , wherein the metal of the further metal layer is aluminum.
9 . The corrosion-resistant permanent magnet of claim 1 , wherein the metal layer is omitted, and the composite coating further comprises, in the order recited, on the layer formed from poly(2-chloro-p-xylylene),
a third metal oxide layer;
a further linker layer; and
a further layer formed from poly(2-chloro-p-xylylene).
10 . The corrosion-resistant permanent magnet of claim 9 , wherein the oxide of the first metal oxide layer is Al 2 O 3 and the oxide of the second metal oxide layer is TiO 2 , or the oxide of the first metal oxide layer is TiO 2 and the oxide of the second metal oxide layer is Al 2 O 3 , or the oxides of the first and second metal oxide layers are Al 2 O 3 , or the oxides of the first and second metal oxide layers are TiO 2 , and/or wherein the oxide of the third metal oxide layer is TiO 2 or Al 2 O 3 .
11 . The corrosion-resistant permanent magnet of claim 9 , further comprising an intermediate metal oxide layer between the layer formed from poly(2-chloro-p-xylylene) and the third metal oxide layer.
12 . The corrosion-resistant permanent magnet of claim 11 , wherein the oxide of the intermediate metal oxide layer is Al 2 O 3 or TiO 2 , and is different from the oxide of the third metal oxide layer.
13 . An intravascular blood pump comprising an electric motor, wherein the electric motor comprises the corrosion-resistant permanent magnet of claim 1 .
14 . The corrosion-resistant permanent magnet of claim 1 , wherein the thickness of the first metal oxide layer is 100 nm.