ISSN 0862-5468 (Print), ISSN 1804-5847 (online) 

Ceramics-Silikáty 32, (1) 65 - 77 (1988)


SOUČINITELÉ SMYKOVÉHO TŘENÍ SKLÁŘSKÝCH VÝROBKŮ

THE COEFFICIENTS OF SHEARING FRICTION OF GLASS WARE


 
Novotný Vladimír 1, Kubišta Petr 1
 
1 Státní výzkumný ústav sklářský, Škroupova 957, 501 92 Hradec Králové
1 State Glass Research Institute, 501 92 Hradec Králové

Sklonným drsnoměrem byl stanoven součinitel statického (f₀) a kinetického (f) smykového tření typických sklářských výrobků s původním, neupraveným povrchem a dále vzorků a výrobků s různě upraveným povrchem - omytým, obroušeným, pokrytým vrstvičkou SnO₂, popř. dopovanou F, s povrchem pokrytým vrstvičkou SnO₂ různých tlouštěk + organickou vrstvičkou, s povrchem zpevněným iontovou výměnou aj. Nejnižší smykové tření výrobků s původním povrchem mají plochá skla (f₀ = 0,17/0,20; f = 0,03/0,10), mírně vyšší trubky a nejvyšší obalová skla (f₀ = 0,23/0,55; f = 0,14/0,39). Po nanesení vrstvičky SnO₂ resp. vrstvičky SnO₂ + organické vrstvičky se statiční součinitelé tření plochých a obalových skel k sobě přiblíží, u kinetického tření se vzájemně vyrovnávají.

The paper presents the results of measuring the static f₀ and kinetic f coefficient of shearing friction by means of a simple roughness meter illustrated in Fig. 1. The instrument serves to determine the friction angle-static, α₀, and kinetic, α, from which the respective coefficient of friction is derived according to equations (3) and (4). In contrast to the studies published so far on shearing friction of glass, the coefficients of friction were determined solely for friction between identical products with the same surface finish. Table I lists some typical literary data on the friction of various materials, Tables II to IV give the values measured by the present authors. The significance of the symbols in the tables is as follows : x - arithmetic mean, sx - standard deviation. The values of the coefficient of friction for 12 glass products with original untreated surfaces are given in Table II: 1 -Float sheet glass 2.8 mm 'untinned' and 'tinned' surface, 2 - Fourcault sheet glass 2.8 mm, 3 - dia. 15 mm tubes of Kovar sealing glass, hand-drawn, 4 through 7 -dia. 6.3 - 40 mm tubes of various types of glass, machine drawn, 8 - toughened circular dishes of Simax glass, pressure moulded, 9, 10 - Euro beer bottles, automated machine production, 11 - 0, 7-litre capacity oil bottles, automated machine production, 12- wide-necked ground coffee bottles, automated machine production. Table III. summarizes the results of measuring the coefficients of shearing friction of sheet glass specimens with surfaces after various treatments: washed, roughened by sanding with SiC, with SnO₂ coating, also doped with F, 10 to 900 nm in thickness, coated with SnO₂ layers with various thicknesses and an organic coating, treated by heating at 650 °C and following various annealing schedules. Table IV lists the measured values of some hollow ware with various types of surface treatment - toughened by ionic exchange, coated with an SnO₂ layer or SnO₂ + organic substances. Among the glass ware types with original surfaces, the lowest shearing friction is exhibited by sheet glass (f₀ = 0.17-0.20, f = 0.03 0.10), mildly higher values by the tubes, and the highest by container glass (f₀ = 0.23-0.55, f = 0.14-0.39). Washing of the original surface will mildly reduce their friction while sanding raises it to values close to those of container glasses; toughening by ion exchange does not practically affect the shearing friction. Application of SnO₂ or SnO₂ + organic layer coatings brings closer the friction coefficients of sheet and container glasses; this applies particularly to the coefficients of kinetic friction which become virtually equal. The friction of container glasses is substantially reduced by these coatings, while that of sheet glasses increases.


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