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1

The mechanical characteristics of phosphate glasses under high temperature and friction-induced cross-linking processes

Pawlak Z., Yarlagadda P. K. D. V., Frost R., Hargreaves D.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 37, nr 2

458-465

EN

Purpose: In the present study, we consider mechanical properties of phosphate glasses under high temperature-induced and under friction-induced cross-linking, which enhance the modulus of elasticity. Design/methodology/approach: Two nanomechanical properties are evaluated, the first parameter is the modulus of elasticity (E) (or Young’s modulus) and the second parameter is the hardness (H). Zinc meta-, pyro - and orthophosphates were recognized as amorphous-colloidal nanoparticles were synthesized under laboratory conditions and showed antiwear properties in engine oil. Findings: Young’s modulus of the phosphate glasses formed under high temperature was in the 60-89 GPa range. For phosphate tribofilm formed under friction hardness and the Young’s modulus were in the range of 2-10 GPa and 40-215 GPa, respectively. The degree of cross-linking during friction is provided by internal pressure of about 600 MPa and temperature close to 1000şC enhancing mechanical properties by factor of 3 (see Fig. 1). Research limitations/implications: The addition of iron or aluminum ions to phosphate glasses under high temperature - and friction-induced amorphization of zinc metaphosphate and pyrophosphate tends to provide more cross-linking and mechanically stronger structures. Iron and aluminum (FeO4 or AlO4 units), incorporated into phosphate structure as network formers, contribute to the anion network bonding by converting the P=O bonds into bridging oxygen. Future work should consider on development of new of materials prepared by sol-gel processes, eg., zinc (II)-silicic acid. Originality/value: This paper analyses the friction pressure-induced and temperature–induced the two factors lead phosphate tribofilm glasses to chemically advanced glass structures, which may enhance the wear inhibition. Adding the coordinating ions alters the pressure at which cross-linking occurs and increases the antiwear properties of the surface material significantly.

2

Journal bearing performance and metrology issues

Sharma S., Hargreaves D., Scott W.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 32, nr 1

98-103

EN

Purpose: In this paper, a radial clearance of a journal bearings and the metrology of the radial clearance measurement is described. Design/methodology/approach: In this experimental study out-of-roundness and radial clearance of journal bearings were measured with high precision and the impact of their metrology was examined on the specific oil film thickness of the bearing. Some metrological issues were emerged and these should be taken into account when bearings are designed. Findings: An investigation showed that the radial clearance measurements can vary from one measuring device to another and the specified clearance may not necessarily meet the design criteria of specific oil film thickness. The study indicates that the radial clearance measurement can differ from one measuring device to another depending upon the precision that can be achieved by the device. The radius of the bearing or the shaft also varies along the circumference, mainly due to out-of-roundness. The out-of-roundness contributes to the error in radial clearance measurement and hence similar to the cut off length specified with the surface roughness, the out-of-roundness needs to be specified with the radial clearance. Practical implications: The radial clearance of a journal bearing is a key design parameter and bearing performance mainly depends upon this parameter. In this paper was showed that the metrology of the radial clearance measurement plays a significant role and not only that the bearing manufacturer or the user of the bearing is aware of this fact but the bearing designer must also take this fact into account while designing bearings Originality/value: This paper showed that The radial clearance is a sensitive micro-geometry parameter and hence metrology plays a vital role in making decisions.

3

External pressure in the hardening of phosphate in tribofilm on iron surfaces

Pawlak Z., Yarlagadda P. K. D. V., Hargreaves D., Frost R., Rauckyta T., Zak S.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 33, nr 1

35-40

EN

Purpose: In the present work we consider our (in progress) spectroscopy study of zinc and iron phosphates under the influence external high pressure to determine zinc ion change coordination from tetrahedral to octahedral (or hexahedral) structure. Design/methodology/approach: The standard equipment is the optical high pressure cell with diamond (DAC). The DAC is assembled and then vibrational or electronic spectra are collected by mounting the cell in an infrared, Raman, EXAFS or UV-visible spectrometer. Findings: Mechanism by which zinc and iron methaphosphate material is transformed to glassy meta-phosphate is enhancing mechanical properties of tribofilm. The two decades of intensive study demonstrates that Zn (II) and Fe (III) ions participate to cross-link network under friction, hardening the phosphate. Research limitations/implications: Transition metal atoms with d orbital have flexible coordination numbers, for example zinc acts as a cross-linking agent increasing hardness, by changing coordination from tetrahedral to octahedral. Perhaps the external pressure effect on the [Zn–(O-P-)4 ] complex causes a transformation to an [Zn –(O-P-)6] grouping. Originality/value: This paper analyses high-pressure spectroscopy which has been applied for the investigation of 3D transition metal ions in solids. When studying pressure effects on coordination compounds structure, we can expect changes in ground electronic state (spin-crossovers), electronic spectra due to structural distortions (piezochromism), and changes in the ligand field causing shifts in the electronic transitions.

4

Development of real-time data filtering for SCADA system

Wiliem L., Hargreaves D., Stapelberg R. F., Yarlagadda P. K. D. V.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 21, nr 2

89-92

EN

Purpose: Purpose to develop a suitable algorithm to filter data from the SCADA system. Design/methodology/approach: A real-time filtering method for SCADA system is developed by capturing the occurence of data change in SCADA data, which is followed by recording several data before this data change occurs. Then, the algorithm is modeled and developed and in the final step an experiment to verify the algorithm is conducted. Finally, the result from the experiment is analysed to check the effectiveness of the algorithm. Findings: As a result, SCADA data analysis will be easier to conduct since only essential information is left. In fact, in comparison to the entire data collection, only around 8-22% of data is changed. Research limitations/implications: By utilizing this algorithm, data will be easier to conduct since only the essential information as a starting point of analyses is left. However, this paper only describes the reasons and steps of data filtering algorithm development, how the algorithm works and the result after it is implemented to analyse data from the SCADA system. Further analyses to the data filtering results haven't been done yet. The next step will be to analyse the results in order to establish the root cause of why the data is changing. Originality/value: It has been noted in many research papers that the SCADA system is able to increase the efficiency of the monitoring itself. However, the SCADA system creates a huge amount of data which is difficult to analyse. This paper proposes a real-time data filtering for the SCADA system. The philosophy that is applied in this algorithm is only to "catch" the occurrence of data change in SCADA data, which is followed by recording several data before this data changes. As a result, SCADA data analysis will be easier to be conducted since only essential information is left. In fact compared to the entire data collection, only around 8-22% of data is changed. Therefore, this method is highly suitable for the SCADA system.

5

The mechanical strength of phosphates under friction-induced cross-linking

Pawlak Z., Yarlagadda P. K. D. V., Frost R., Hargreaves D.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 17, nr 1-2

201--204

EN

Purpose: In the present study, we consider mechanical properties of phosphate glasses under high temperature-induced and under friction-induced cross-linking, which enhance the modulus of elasticity. Design/methodology/approach: Two nanomechanical properties are evaluated, the first parameter is the modulus of elasticity (E) (or Young’s modulus) and the second parameter is the hardness (H). Zinc meta-, pyro - and orthophosphates were recognized as amorphous-colloidal nanoparticles were synthesized under laboratory conditions and showed antiwear properties in engine oil. Findings: Young’s modulus of the phosphate glasses formed under high temperature was in the 60-89 GPa range. For phosphate tribofilm formed under friction hardness and the Young’s modulus were in the range of 2-10 GPa and 40-215 GPa, respectively. The degree of cross-linking during friction is provided by internal pressure of about 600 MPa and temperature close to 1000°C enhancing mechanical properties by factor of 3 (see Fig 1). Research limitations/implications: The addition of iron or aluminum ions to phosphate glasses under high temperature - and friction-induced amorphization of zinc metaphosphate and pyrophosphate tends to provide more cross-linking and mechanically stronger structures. Iron and aluminum (FeO4 or AlO4 units), incorporated into phosphate structure as network formers, contribute to the anion network bonding by converting the P=O bonds into bridging oxygen. Future work should consider on development of new of materials prepared by sol-gel processes, eg., zinc (II)-silicic acid. Originality/value: This paper analyses the friction pressure-induced and temperature–induced the two factors lead phosphate tribofilm glasses to chemically advanced glass structures, which may enhance the wear inhibition. Adding the coordinating ions alters the pressure at which cross-linking occurs and increases the antiwear properties of the surface material significantly