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Mill Rolls and Their Bearings
Published in William L. Roberts, Cold Rolling of Steel, 2017
In the Rockwell hardness test, developed in 1921, the hardness number obtained represents the additional depth to which a test ball or sphero-conical diamond test penetrator is driven by a heavy load beyond the depth of a previously applied light load, as illustrated in Figure 4-40. The minor load (10 kgs.) is applied to the penetrator first, the major load (60, 100, or 150 kgs.) applied, the major load is then removed without moving the surface under test, and the hardness number is then automatically indicated on a gage. The entire test requires only five or ten seconds and was designed to measure the hardness of all types of metals, both hard and soft, in any shape or form. The incremental depth of penetration for each point of hardness of the Rockwell scale is 0.00008 inches.
Arcing Contact Materials
Published in Paul G. Slade, Electrical Contacts, 2017
In the following sections of this chapter, some of the typical properties of the materials are listed in tables. A further listing of properties is given in Chapter 24. The properties listed in brochures of several manufacturers along with available standards were utilized to determine typical values for composition, density, hardness, and conductivity [2–5] For material hardness the Vickers scale is used although many companies list these values using the Rockwell scale. Most individual contacts are too small in size, however, for accurate measurement using the Rockwell scale. Vickers is therefore the better choice, because it allows comparison of hardness regardless of the contact size, and, more importantly, the Vickers values allow theoretical calculation of contact resistance using the following equation from Chapter 1 (see also Chapter 24, Section 24.2[f]): () Rc=ρ(πH/4F)1/2H is hardness in N (Newtons) mm−2, F is force expressed as N, ρ is resistivity in Ω mm. Note: Since many contact catalogs list properties in terms of Vickers, kg mm−2, you can convert these values to N mm−2 by multiplying the value by the factor 9.81, also most catalogs use conductivity (m Ω−1 mm−2) that can be converted to resistivity in terms of Ω mm by taking the reciprocal of the value and multiplying it by 10−3. For example if a silver cadmium oxide contact has hardness listed as 80 HV and a conductivity of 48 m Ω−1 mm−2. The constriction resistance for a 0.5 N contact force is estimated as follows: 80×9.81=784.8Nmm−2hardness(1/48)×10−3=20.810−6ΩmmRc=0.73×10−3Ω
Insight Into Surface Texture-Induced Dual Effects on Friction of WC-Co Dry Sliding Against Continuous Carbon Fiber-Reinforced Thermoplastic and Thermosetting Composites
Published in Tribology Transactions, 2022
Xin Dong, Chaoyang Dong, Bo Wu
Cylindrical discs (ϕ50 × 6 mm) made of sintered WC-Co (6 wt% Co) were purchased from a professional tool research institute. Disc hardness derived from the material supplier was approximately 90 HRA (Rockwell scale A hardness (30)). One bottom surface of each disc was mirror-polished to an areal average roughness (Sa) of less than 0.05 μm (measured by laser confocal scanning microscope with 10 nm resolution in sample height, LCSM). Note that manufacturing processes were not provided by the vendor. The surface morphology of the polished WC-Co disc was examined using scanning electron microscopy (SEM), as shown in Fig. S-1a (Supplementary Materials). Energy-dispersive x-ray spectroscopy (EDS) was used to characterize the elemental composition: 11.0 wt% C, 86.3 wt% W, and 2.7 wt% Co (Fig. S-1b).
Evaluation of surface disinfection methods to inactivate the beta coronavirus Murine Hepatitis Virus
Published in Journal of Occupational and Environmental Hygiene, 2022
R. L. Hardison, S. W. Nelson, D. Barriga, N. Feliciano Ruiz, J. M. Ghere, G. A. Fenton, D. J. Lindstrom, R. R. James, M. J. Stewart, S. D. Lee, M. W. Calfee, S. P. Ryan, M. W. Howard
Fatigue-Resistant 301 SS (0.03 cm thick; hardness rating of C40 on Rockwell Scale; meeting ASTM A666 specifications) and SBR (0.16 cm thick) were purchased from McMaster-Carr (Aurora, OH). Bus Seat Fabric was sourced from American Seating (Item #00333uw1; Grand Rapids, MI). Drywall tape (Item# 11752) was purchased from Lowe’s Home Improvement (Columbus, Ohio) and painted with Latex Eggshell Ultra White Tintable Interior Paint (Item# 773956; Lowe’s). All materials were cut into 7.7 cm x 1.9 cm coupons using hand tin snips (301 SS), a hydraulic cutter (SBR), or scissors (paint). Once cut, SS coupons were cleaned by soaking in a 1:100 diluted Liqui-Nox solution at pH 8.5 (Alconox, White Plains, NY), followed by rinsing in distilled water. Rubber coupons were cleaned with 70% isopropanol and wiped with a cloth. All coupons were air-dried, packaged in heat-sealed polyethylene (PE) tubing, and sterilized by Electron Beam (E-BEAM Services, Inc., Lebanon, OH; dose of 40kGy).
Efficacy of detergent-based cleaning methods against coronavirus MHV-A59 on porous and non-porous surfaces
Published in Journal of Occupational and Environmental Hygiene, 2022
Rachael L. Hardison, Sarah W. Nelson, Daniela Barriga, Jessica M. Ghere, Gabrielle A. Fenton, Ryan R. James, Michael J. Stewart, Sang Don Lee, M. Worth Calfee, Shawn P. Ryan, Megan W. Howard
Fatigue-Resistant 301 SS (SS; 0.03 cm thick; hardness rating of C40 on Rockwell Scale; meeting ASTM A666 specifications) and Impact-Resistant ABS (0.95 cm thick; hardness rating of R101-R109; meeting UL 94 HB specifications) was purchased from McMaster-Carr (Aurora, OH). Formica laminate was purchased from Home Depot (Columbus, Ohio). SF was sourced from American Seating (Item # 00333uw1; Grand Rapids, MI). All materials were cut into 7.62 cm x 1.91 cm (3 in x 0.75 in) coupons. Once cut, SS and ABS coupons were cleaned by soaking in a 1:100 diluted Liqui-Nox solution at pH 8.5 (Alconox, White Plains, NY), followed by rinsing in distilled water. Formica coupons were cleaned with 70% isopropanol and wiped with a cloth. All coupons were air-dried and packaged in heat-sealed polyethylene (PE) in packs of nine and sterilized by Electron Beam (E-BEAM Services, Inc., Lebanon, OH) with a dose of 40kGy.