Valves having protective coatings
A shear valve for use in a high performance liquid chromatography system. The shear valve includes a first valve member having a plurality of first fluid-conveying features, and a second valve member having one or more second fluid-conveying features. The second valve member is movable, relative to the first valve member, between a plurality of discrete positions such that, in each of the discrete positions, at least one of the one or more second fluid-conveying features overlaps with multiple ones of the first fluid conveying features to provide for fluid communication therebetween. At least one of the first and second valve members is at least partially coated with a protective coating that includes an adhesion interlayer and a diamond-like carbon (DLC) layer. The DLC layer is deposited on the adhesion interlayer via filtered cathodic vacuum arc (FCVA) deposition.
1. A method comprising:
depositing an adhesion interlayer on a shear valve member via filtered cathodic vacuum arc (FCVA) deposition, the adhesion layer including an interlayer material consisting of titanium; and
depositing a diamond-like carbon (DLC) layer on the adhesion layer via FCVA deposition;
wherein the diamond-like carbon layer on the adhesion layer has a thickness of about 0.5 microns to about 2.5 microns and a roughness Ra of 5 nanometers or less.
2. The method of claim 1 , wherein the shear valve member is a stator, and wherein depositing the adhesion interlayer comprises depositing the adhesion interlayer on a stator interface of the stator.
3. The method of claim 1 , wherein the adhesion interlayer is deposited at a process temperature below 80 degrees Celsius.
4. The method of claim 1 , wherein the diamond-like carbon layer is deposited at a process temperature below 80 degrees Celsius.
5. The method of claim 1 , further comprising:
polishing a surface region of the shear valve member to a roughness of less than 25 nanometers,
wherein the adhesion interlayer and the DLC layer are deposited on the surface region.
6. The method of claim 1 , further comprising adjusting a workpiece bias voltage during deposition of the DLC layer to provide the DLC layer with a hardness of about 30 GPa to about 60 GPa.
7. The method of claim 1 , wherein the deposited adhesion interlayer has a thickness of about 100 nanometers to about 500 nanometers.
8. The method of claim 1 , wherein each of the adhesion interlayer and the DLC layer has a thickness greater than 5 nanometers.
9. The method of claim 1 , wherein the roughness Ra of the DLC layer is achieved without post-polishing.