Abstract: An electronic device such as a wristwatch may include a conductive housing. A corrosion-resistant coating may be deposited on the conductive housing. The coating may include transition layers and an uppermost alloy layer. The transition layers may include a chromium seed layer on the conductive housing and a chromium nitride layer on the chromium seed layer. The uppermost alloy layer may include TiCrCN or other alloys and may provide the coating with desired optical reflection and absorption characteristics. The transition layers may include a minimal number of coating defects, thereby eliminating potential sites at which visible defects could form when exposed to salt water. This may allow the electronic device to exhibit a desired color and to be submerged in salt water without producing undesirable visible defects on the conductive housing structures.

Abstract: An electronic device may be provided with conductive structures such as conductive housing structures. A visible-light-reflecting coating may be formed on the conductive structures. The coating may have adhesion and transition layers, an opaque coloring layer on the adhesion and transition layers, and a two-layer thin-film interference filter on the opaque coloring layer. The two-layer thin-film interference filter may an uppermost diamond-like carbon (DLC) or CrSiCN layer and a lowermost SiCrCN layer. The coating may exhibit a dark blue or black color that has a relatively uniform visual response even when the underlying conductive structures have a three-dimensional shape.

Abstract: An electronic device may be provided with conductive structures such as a titanium housing wall. A visible-light-reflecting coating may be formed on the titanium housing wall. The coating may have adhesion and transition layers and an uppermost opaque coloring layer. In a first example, the uppermost opaque coloring layer includes CrC on a CrSiN transition layer. In a second example, the uppermost opaque coloring layer includes CrN on a CrN transition layer. The coating may exhibit a relatively uniform metallic silver or gray color that is smudge resistant even when the underlying titanium housing wall has a three-dimensional shape.

Abstract: An electronic device such as a power charger may include a conductive contact that conveys power signals. A coating may have adhesion and transition layers on the contact. The coating may have a thin-film interference filter having an uppermost layer that includes diamond-like carbon (DLC). If desired, the thin-film interference filter may have additional DLC layers stacked under the uppermost layer. The DLC layer(s) may include nitrogen to optimize corrosion resistance. The DLC layer(s) may include first and second metal dopants such as tungsten and chromium to optimize the electrical resistance and conductivity of the coating. The coating may exhibit a deep black, grey, and/or blue color.

Abstract: An electronic device may be provided with conductive structures such as conductive housing structures. A visible-light-reflecting coating may be formed on the conductive structures. The coating may have adhesion and transition layers and a thin-film interference filter on the adhesion and transition layers. The thin-film interference filter may be a four-layer interference filter stacked directly onto the adhesion and transition layers and having an uppermost SiCrN layer, a lowermost SiN layer, and interleaved SiH and SiN layers. If desired, an opaque coloring layer such as a Cr layer may be disposed between the interference filter and the adhesion and transition layers. The coating may exhibit a deep red or orange color that has a relatively uniform visual response even when the underlying conductive structures have a three-dimensional shape.

Abstract: Non-cosmetic quality aluminum substrates are given a cosmetic finish by applying a PVD coating to the substrate. An enclosure for an electronic device can include an aluminum substrate including a 6000 series aluminum or 7000 series aluminum, a PVD coating disposed on the substrate, and a protective underlayer disposed between the aluminum substrate and the PVD coating.

Abstract: An electronic device may include conductive structures such as conductive housing structures. A high-brightness, visible-light-reflecting coating may be formed on the conductive structures. The coating may have adhesion and transition layers and an uppermost coloring layer on the adhesion and transition layers. At least the uppermost coloring layer may be deposited using a high impulse magnetron sputtering (HiPIMS) process. The uppermost coloring layer may include a TiCrN film, a TiCrCN film, a TiCN film, or a metal nitride film that contains Ti, Zr, Hf, or Cr. The coating may exhibit a high-brightness gold color.

Abstract: A coating-substrate combination includes: a Ni-based superalloy substrate comprising, by weight percent: 2.0-5.1 Cr; 0.9-3.3 Mo; 3.9-9.8 W; 2.2-6.8 Ta; 5.4-6.5 Al; 1.8-12.8 Co; 2.8-5.8 Re; 2.8-7.2 Ru; and a coating comprising, exclusive of Pt group elements, by weight percent: Ni as a largest content; 5.8-9.3 Al; 4.4-25 Cr; 3.0-13.5 Co; up to 6.0 Ta, if any; up to 6.2 W, if any; up to 2.4 Mo, if any; 0.3-0.6 Hf; 0.1-0.4 Si; up to 0.6 Y, if any; up to 0.4 Zr, if any; up to 1.0 Re, if any.

Abstract: An electronic device may include conductive structures such as conductive housing structures. A high-brightness, visible-light-reflecting coating may be formed on the conductive structures. The coating may have adhesion and transition layers and an uppermost coloring layer on the adhesion and transition layers. At least the uppermost coloring layer may be deposited using a high impulse magnetron sputtering (HiPIMS) process. The uppermost coloring layer may include a TiCrN film, a TiCrCN film, a TiCN film, or a metal nitride film that contains Ti, Zr, Hf, or Cr. The coating may exhibit a high-brightness gold color.

Abstract: An electronic device such as a wristwatch may be provided with conductive structures. The conductive structures may include a sensor electrode for an electrocardiogram (ECG) sensor. A coating may be disposed on the sensor electrode to reflect particular wavelengths of visible light so that the sensor electrode exhibits a desired color. The coating may include adhesion and transition layers on the sensor electrode, an opaque coloring layer on the adhesion and transition layers, and a thin-film interference filter on the opaque coloring layer. The thin-film interference filter may have an uppermost diamond-like carbon (DLC) layer. The DLC layer may contribute to the color response of the coating while concurrently minimizing noise in ECG waveforms gathered by the ECG sensor using the sensor electrode.

Abstract: An electronic device may be provided with conductive structures such as conductive housing structures. A visible-light-reflecting coating may be formed on the conductive structures. The coating may have adhesion and transition layers, an opaque coloring layer on the adhesion and transition layers, and a three-layer thin-film interference filter on the opaque coloring layer. The three-layer thin-film interference filter may have an uppermost SiC layer, a lowermost SiCrCN layer, and a CrC layer interposed between the SiC layer and the SiCrCN layer. The opaque color layer may be a CrSiCN layer. The coating may exhibit a light violet color that has a relatively uniform visual response even when the underlying conductive structures have a three-dimensional shape.

Abstract: An electronic device may have a housing. The device may include metal structures such as a metal member forming a portion of the housing, a portion of a strap, or other portions of the device. A gold-containing coating such as a layer of elemental gold or a gold alloy may cover the metal member to provide the metal member with a gold appearance or other desired appearance. To protect the metal member and the gold-containing coating, the metal member and gold-containing coating may be covered with a protective coating layer such as an organic protective layer. The organic protective layer may have a fluoropolymer layer with thiol coupling groups to promote adhesion to the gold-containing layer or may contain a polymer layer with silane and thiol coupling groups that serves as an adhesion promotion layer for an overlapping fluoropolymer layer with silane coupling groups.

Abstract: An electronic device may include conductive structures having a visible-light-reflecting coating. The coating may include a seed layer, transition layers, a neutral-color base layer, and an uppermost layer that forms a single-layer interference film. The neutral-color base layer may be opaque to visible light. The interference film may include silicon and may have an absorption coefficient between 0 and 1. The interference film may include, for example, CrSiN or CrSiCN. The composition of the interference film, the thickness of the interference film, and/or the composition of the base layer may be selected to provide the coating with a desired color near the middle of the visible spectrum (e.g., at green wavelengths). The color may be relatively stable even if the thickness of the coating varies across its area.

Abstract: An electronic device may include conductive structures having a visible-light-reflecting coating. The coating may include a seed layer, transition layers, a neutral-color base layer, and an uppermost layer that forms a single-layer interference film. The neutral-color base layer may be opaque to visible light. The interference film may include silicon and may have an absorption coefficient between 0 and 1. The interference film may include, for example, CrSiCN or CrSiC. The composition of the interference film, the thickness of the interference film, and/or the composition of the base layer may be selected to provide the coating with a desired color in the visible spectrum (e.g., at blue or purple wavelengths). The color may be relatively stable even if the thickness of the coating varies across its area.

Abstract: An electronic device may be provided with conductive structures such as conductive housing structures. A visible-light-reflecting coating may be formed on the conductive structures. The coating may have adhesion and transition layers and a multi-layer thin-film interference filter on the adhesion and transition layers. The multi-layer thin-film interference filter may have an uppermost SiCrN layer, a lowermost TiN layer, and a set of SiN layers interleaved with a set of SiH layers. The coating may exhibit an orange, yellow, or red color that has a relatively uniform visual response at different viewing angles even when the underlying conductive structures have a three-dimensional shape.

Abstract: A coating-substrate combination includes: a Ni-based superalloy substrate comprising, by weight percent: 2.0-5.1 Cr; 0.9-3.3 Mo; 3.9-9.8 W; 2.2-6.8 Ta; 5.4-6.5 Al; 1.8-12.8 Co; 2.8-5.8 Re; 2.8-7.2 Ru; and a coating comprising, exclusive of Pt group elements, by weight percent: Ni as a largest content; 5.8-9.3 Al; 4.4-25 Cr; 3.0-13.5 Co; up to 6.0 Ta, if any; up to 6.2 W, if any; up to 2.4 Mo, if any; 0.3-0.6 Hf; 0.1-0.4 Si; up to 0.6 Y, if any; up to 0.4 Zr, if any; up to 1.0 Re, if any.

Abstract: A coating-substrate combination includes: a Ni-based superalloy substrate comprising, by weight percent: 2.0-5.1 Cr; 0.9-3.3 Mo; 3.9-9.8 W; 2.2-6.8 Ta; 5.4-6.5 Al; 1.8-12.8 Co; 2.8-5.8 Re; 2.8-7.2 Ru; and a coating comprising, exclusive of Pt group elements, by weight percent: Ni as a largest content; 5.8-9.3 Al; 4.4-25 Cr; 3.0-13.5 Co; up to 6.0 Ta, if any; up to 6.2 W, if any; up to 2.4 Mo, if any; 0.3-0.6 Hf; 0.1-0.4 Si; up to 0.6 Y, if any; up to 0.4 Zr, if any; up to 1.0 Re, if any.

Abstract: An electronic device may include conductive structures with a light-reflecting coating. The coating may have a two or four-layer thin-film interference filter. The two-layer filter may have a CrN layer and an SiCrN layer. The four-layer filter may have two CrN layers and two SiCrN layers. The two-layer filter may be used to coat relatively small conductive components. The four-layer filter may be used to coat a conductive housing sidewall. Both types of interference filter may produce a relatively uniform light blue color despite variations in coating thickness produced on account of the geometry of the underlying conductive structure.

Abstract: A method of forming a surface coating on a component of an electronic device can include depositing an aluminum layer including at least about 0.05 weight percent (wt %) of a grain refiner on a surface of the component by a physical vapor deposition process, and anodizing the aluminum layer to form an anodized aluminum oxide layer having a L* value greater than about 85 in the CIELAB color space.

Abstract: An electronic device may include conductive structures such as conductive housing structures. A high-brightness, visible-light-reflecting coating may be formed on the conductive structures. The coating may have adhesion and transition layers and an uppermost coloring layer on the adhesion and transition layers. At least the uppermost coloring layer may be deposited using a high impulse magnetron sputtering (HiPIMS) process. The uppermost coloring layer may include a TiCrN film, a TiCrCN film, a TiCN film, or a metal nitride film that contains Ti, Zr, Hf, or Cr. The coating may exhibit a high-brightness gold color.