A.Broese van Groenou's research while affiliated with Philips and other places

Publications (13)

Patent
Full-text available
Magnetic head having a head face (5) and comprising a head structure composed of thin layers and provided with a transducing element (E11), in which different materials occurring in different areas are present in the head face. The head face is provided with a first layer (31) of a material which is more sensitive to corrosion than other materials...
Article
The introduction of the digital compact cassette system into the consumer market imposed some severe requirements on the durability of the thin-film heads used in this system. The reliability of the head's record and playback functions has to be maintained under a wide variety of climatic conditions and tape types, as a consequence of the system's...
Article
A survey is given of the concepts used in discussing the friction and wear of tapes, flexidisks and hard disks. The concepts are illustrated by examples taken from problems in video recording. The contact between two bodies is located in the tips of asperities. The distribution of the heights can be measured and gives the standard deviation which,...
Article
By sliding a 0.25 mm radius ruby sphere on a (111) MnZn ferrite crystal, grooves have been made at speeds from 4 to 400 m sec–1, at loads from 0.5 to 4 N and after 1 to 1000 passes. The deformation is observed by microscopy and profilometry. For a single pass slip lines are observed in all directions of sliding, above a load that increases with sli...
Article
The anisotropy in plastic deformation of MnZn ferrite is investigated by R = 0.25 mm sphere indentation and sliding experiments. Sliding experiments are conducted at a speed of υ = 400 μs−1 on a series of crystal planes in directions perpendicular to [011̄]. The first visible deformation is found to be slip lines emerging on the surface. The thresh...
Article
The wear anisotropy of MnZn ferrite against tape has been investigated in a video tape recorder and in a sphere-on-tape tester. The wear rate is measured on a series of crystal faces corresponding to the contact planes of video heads with a {110} side plane, in both running directions of the tape. The experiments in the recorder and the sphere-on-t...
Article
A level difference is formed between the metal and oxide in hybrid heads, such as metal-in-gap and sandwich heads, when used against tapes based on Fe pigment (MP) or on metal-evaporated tapes (MF). The level difference depends on a number of factors. Model experiments with soft metals show tape particles to be embedded. The length of metal layer a...
Article
Friction between tape and guiding pins or recording heads is determined by the mechanical interaction of the microscopic asperities on the two surfaces in contact. The friction coefficient is given by f =τ<sub>y</sub>/ P <sub>asp</sub> where τ<sub>y </sub> is the shear strength at which the asperities yield irreversibly and P <sub>asp</sub> is the...
Conference Paper
Various limitations in the design of recording heads are reviewed. Track definition and gap length, the need for small heads and possible improvements in the shape of heads, coil chambers and magnetic flux guides, and the requirements for the materials to be used in metal-in-gap heads and sandwich heads are considered. With respect to future develo...
Article
By sliding a ruby sphere (0.25 mm in radius) on various MnZn ferrite crystals quantitative information has been obtained on the groove depth at speeds of 0.4–400 μm s−1 at loads of 1–10 N and after 1–1000 passes. Above a certain threshold, a simple empirical relation is found between depth and load, Ig10(speed) and Ig10(passes) at 20 °C. The thresh...
Article
By sliding a 0.25 mm radius ruby sphere on a (1 1 0) Mn-Zn ferrite crystal grooves have been made at speeds from 0.4 to 400 m sec–1, at loads from 1 to 7 N and after 1 to 100 passes. The temperature was varied from 20 to 290 C. As in indentations, the slip patterns are found on {1 0 0}, {1 1 1} and {1 1 0} slip systems, due to 1 1 0 slip along eith...
Article
The formation of grooves and cracks in polycrystalline ceramic materials has been investigated by means of a sliding 0.5 mm ruby sphere. At speeds from 4 μm s−1 to 0.4 mm s−1, at loads from 1 to 6 N and after 1–5000 passes the deformation of a number of ferrites (hardness, 7 GPa) has been observed.In polycrystalline nickel zinc ferrites (NiaZn1−aFe...

Citations

... Wear can be restricted by changing material characteristics or solid surface characteristics by "surface design" forms (usually referred to surface finishing) or using greases (for frictional or glue wear). Contingent upon operational parameters, for example, type of material, pressure and sliding speed, diverse frictional temperatures happen that offer ascent to different power misfortunes [22][23][24]. Dry friction consistently produces heat and thusly dispersion forms. Along these lines, dry sliding contact makes surface twisting resulting in a deformation of the crystal lattice and greater convergence of separations. ...
... And for HCP crystal like sapphire, wear rate on basal plane along [1120] was lower than [1010] 5 . After these pioneering works on anisotropic friction and wear properties, more efforts have been made in exploring directionality of tribological properties for various kind of materials [8][9][10][11][12][13][14][15][16][17] . As wurtzite single crystal material, the anisotropic properties of GaN also have been studied for decades, such as Young's modulus, hardness, shear strength, etc 18-21 . ...
... Its good mechanical and tribological properties permit its use as a protective coating material to enhance the surface properties of materials and fortify the substrate material against environmental degradation while retaining the substrate bulk material properties. Chromium oxides have been investigated as a potential protective coating material on read and write-heads in magnetic recording units, in optical applications as solar absorber material and as black matrix films in liquid crystal displays [6][7][8]. The other potential application areas include an electrode material for electrochromic windows and solar energy shielding films for windows [9]. ...
... The increased spacing caused by PTR results in lower write density, so the recession must be minimized. PTR has been observed and measured by numerous authors678910111213141516. Scott and Bhushan [17] review the recent research on PTR in tape heads. ...
... By investigating the effect of operating conditions such as tape speed and tape tension in conjunction with design parameters such as roller diameter, surface quality, hardness and coating, the frictional behaviour between tape and roller can be optimized to reduce LTM and tape wear. Broese van Groenou [3] stated that the friction between tape and guiding pins is determined by the mechanical interaction of the microscopic asperities on the two surfaces in contact. He defined the friction coefficient as ...