Apparatus and methods associated with an enclosure or structure including two sections that are adapted with a snap-fit interlocking structure. Various embodiments of the enclosure or structures are formed with various case hardening or embrittlement processes to increase embrittlement or hardness of the enclosure or structure so as to create a structure or enclosure which has a desired fragmentation capacity while still maintaining sufficient material properties to permit snap-fit insertion of one section into another section and withstand substantial impacts. Embodiments also provide an interlocking structure that minimizes differences in fragmentation or fracturing capacity as contrasted with other portions of the structure or enclosure. An embodiment of the invention includes an enclosure where one section of the enclosure or structure has a first thickness and the second section has a second thickness, wherein the first and second thicknesses are different. In some embodiments, one section is thinner than another section.

In one or more embodiments, a shielding device is provided to shield a bore of a shaft against surface treatment, the shielding device including a sleeve to be at least partially received within the bore, the sleeve defining on its side wall a through-aperture and being of a first cross-sectional dimension when the through-aperture is at a rest position, and a pin to be at least partially received within the sleeve, the sleeve being of a second cross-sectional dimension greater than the first cross-sectional dimension when the through-aperture is at an expanded position with the pin being at least partially received within the sleeve.

In one or more embodiments, a shielding device is provided to shield a bore of a shaft against surface treatment, the shielding device including a sleeve to be at least partially received within the bore, the sleeve defining on its side wall a through-aperture and being of a first cross-sectional dimension when the through-aperture is at a rest position, and a pin to be at least partially received within the sleeve, the sleeve being of a second cross-sectional dimension greater than the first cross-sectional dimension when the through-aperture is at an expanded position with the pin being at least partially received within the sleeve.

An apparatus for masking an article with masking material is disclosed. The apparatus generally includes a spray head connected to a primary channel which forms a passage for the masking material. This channel has two sections, the first of which terminates in a junction with the spray head and is angled from the second section. In addition, the apparatus has at least one secondary channel which forms an air passage and is attached to the primary angled channel.

An apparatus for masking an article with masking material is disclosed. The apparatus generally includes a spray head connected to a primary channel which forms a passage for the masking material. This channel has two sections, the first of which terminates in a junction with the spray head and is angled from the second section. In addition, the apparatus has at least one secondary channel which forms an air passage and is attached to the primary angled channel.

A low sludge trivalent chromium based conversion coating bath is provided which forms corrosion resistant coatings on aluminum and aluminum alloys by immersion in aqueous solutions containing trivalent chromium ions and fluorometallate ions followed by optional rinsing. Trivalent chromium coated aluminum also serves as an effective base for paint primers.

A low sludge trivalent chromium based conversion coating bath is provided which forms corrosion resistant coatings on aluminum and aluminum alloys by immersion in aqueous solutions containing trivalent chromium ions and fluorometallate ions followed by optional rinsing. Trivalent chromium coated aluminum also serves as an effective base for paint primers.

A strip casting apparatus having a roll shell with a nitrided inner diameter surface mounted on a steel core and method of manufacturing the same. The inner diameter of a steel roll shell may be nitrided by ion or plasma nitriding. The nitriding process can form tight, crack free nitride layer that provides a corrosion resistant barrier and exhibits a surface hardness that is greater than the surface hardness of the steel core and that improves galling resistance while maintaining efficient heat transfer of the roll shell. After nitriding, the roll shell can be shrink fit over a steel core.

A strip casting apparatus having a roll shell with a nitrided inner diameter surface mounted on a steel core and method of manufacturing the same. The inner diameter of a steel roll shell may be nitrided by ion or plasma nitriding. The nitriding process can form tight, crack free nitride layer that provides a corrosion resistant barrier and exhibits a surface hardness that is greater than the surface hardness of the steel core and that improves galling resistance while maintaining efficient heat transfer of the roll shell. After nitriding, the roll shell can be shrink fit over a steel core.

This invention relates to a surface heat treatment method in a salt bath at low temperature, suitable for partially hardening the surface of a workpiece through heat treatment, including plating the surface of a workpiece with a first metal layer; partially peeling the first metal layer; heat treating the workpiece at a temperature of 400 to 500 C. for a predetermined period of time; and totally peeling the first metal layer. Thereby, low-temperature heat treatment is effective at heat treating the workpiece while minimizing deterioration of corrosion resistance.