The Use of Abrasives in Winter Maintenance, TR-434, 2001

The use of abrasives in winter maintenance is a well-established practice. The sand or other abrasive is intended to increase friction between vehicles and the (often snow or ice covered) pavement. In many agencies (and in many Iowa Counties, the focus of this study) the use of sand is a standard part of winter maintenance. Yet very little information exists on the value of sanding as a winter maintenance procedure. Some studies suggest that friction gains from sanding are minimal. In addition, there are increasing environmental concerns about sanding. These concerns focus on air quality and stormwater quality issues. This report reviews the state of the practice of abrasive usage in Iowa Counties, and classifies that usage according to its effectiveness. Possible changes in practice (with respect to abrasive usage) are presented and discussed.

Evaluation of grinding fluids in the grinding of a martensitic valve steel with CBN and alumina abrasives

In this paper the performances of different cutting fluids and grinding wheel types were analysed in the grinding of SAE HVN-3 workpieces. The resulting residual stress, wheel wear and roughness were evaluated. The influence of the cutting fluid jet velocity v(j) was also analysed. As a conclusion, the lubrication ability seems to be the governing factor in the cutting fluid performance. The use of CBN wheels can significantly reduce the thermal damage in grinding, leading to compressive residual stresses. The CBN wheel and the cutting oil give an optimum combination for performing this grinding operation.

Influence of different toothpaste abrasives on the bristle end-rounding quality of toothbrushes

To evaluate the influence of different toothpaste abrasives on the bristle wear and bristle tip morphology of toothbrushes with different degrees of hardness. Material and methods Ninety samples of bovine incisor teeth were used in this study. The samples were randomly divided into three groups according to the bristle hardness of the toothbrush used: soft bristles (S); extra-soft bristles (ES); hard bristles (H). The toothbrushes of each group were randomly divided into six subgroups with five toothbrushes each, according to the abrasive of the toothpaste used in the simulation: Negative control (distilled water); toothpaste 1 (silica); toothpaste 2 (hydrated silica); toothpaste 3 (calcium carbonate, calcium bicarbonate and silica); toothpaste 4 (tetrapotassium pyrophosphate, silica and titanium dioxide); toothpaste 5 (calcium carbonate). The samples were placed in a toothbrushing simulating machine that simulating three months of brushing. The toothbrush bristles were evaluated by the bristle wear index, and the bristle tips morphology was evaluated by the bristle tip morphology index. Results The ES brush presented the highest bristle wear among the toothbrushes. Additionally, the S brushes showed better morphology of the bristles followed by ES and H brushes. The type of abrasive only influenced the bristle tip morphology of the ES brushes. The toothpaste 3 induced the worse bristle tip morphology than all the other toothpastes. Conclusions Different abrasives have influence only on the bristle tip morphology of the ES brushes.

Influence of different toothpaste abrasives on the bristle end-rounding quality of toothbrushes

ObjectivesTo evaluate the influence of different toothpaste abrasives on the bristle wear and bristle tip morphology of toothbrushes with different degrees of hardness.Material and methodsNinety samples of bovine incisor teeth were used in this study. The samples were randomly divided into three groups according to the bristle hardness of the toothbrush used: soft bristles (S); extra-soft bristles (ES); hard bristles (H). The toothbrushes of each group were randomly divided into six subgroups with five toothbrushes each, according to the abrasive of the toothpaste used in the simulation: Negative control (distilled water); toothpaste 1 (silica); toothpaste 2 (hydrated silica); toothpaste 3 (calcium carbonate, calcium bicarbonate and silica); toothpaste 4 (tetrapotassium pyrophosphate, silica and titanium dioxide); toothpaste 5 (calcium carbonate). The samples were placed in a toothbrushing simulating machine that simulating three months of brushing. The toothbrush bristles were evaluated by the bristle wear index, and the bristle tips morphology was evaluated by the bristle tip morphology index.ResultsThe ES brush presented the highest bristle wear among the toothbrushes. Additionally, the S brushes showed better morphology of the bristles followed by ES and H brushes. The type of abrasive only influenced the bristle tip morphology of the ES brushes. The toothpaste 3 induced the worse bristle tip morphology than all the other toothpastes.ConclusionsDifferent abrasives have influence only on the bristle tip morphology of the ES brushes.

Effect of toothpastes with different abrasives on eroded human enamel: an in situ/ex vivo study

The aim of the present study was to investigate the abrasive effect of CaCO3 and SiO2-based fluoride-free experimental toothpastes on eroded human permanent dental enamel and evaluate the effectiveness of waiting periods between acid exposure and tooth brushing. Twelve volunteers wore palatal appliances containing human enamel blocks for two periods of five days each. The appliances were immersed in a soft drink for five minutes four times a day (9:00 am, 11:00 am, 2:00 pm and 4:00 pm). On two occasions, two blocks were not submitted to additional treatment; two blocks were brushed (30 s) either with a CaCO3 or SiO2 toothpaste immediately after erosion and two blocks were brushed 1 h after erosion. Thus, the sample was divided into six groups: erosion alone (CaCO3 and SiO2 control); brushing with fluoride- free toothpaste (CaCO3 immediate and 1 h after erosion; SiO2 immediate and 1 h after erosion). Significant differences in wear depth were found between the enamel blocks in the CaCO3 immediate and 1 h after erosion groups and the blocks in the CaCO3 control group (p=0.001; p=0.022). No significant differences were found regarding the change in roughness and wear depth between blocks submitted to immediate abrasion and 1 h after erosion (CaCO3 and SiO2). The data revealed that surface roughness and wear depth is increased when erosion is combined with dental abrasion, regardless of the abrasive used. Waiting for 1 h to brush the eroded blocks offered no protective effect.

... Abrasives; products of Canada; technology and application ...

In lower right corner of t.-p.: no. 673, 675, 677, 699, respectively.

The mineral industry of the British empire and foreign countries. Statistics, 1919-1921. Abrasives.

At head of title: Imperial Mineral Resources Bureau.

The mineral industry of the British empire and foreign countries. Abrasives.

At head of title: Imperial Institute.

The mineral industry of the British empire and foreign countries. Statistics, 1920-1922. Abrasives.

At head of title: Imperial Mineral Resources Bureau.

Evaluation technique for determining wheel performance in the grinding of aerospace materials

Nickel-based super alloys are used in a variety of applications in which high-temperature strength and resistance to creep, corrosion, and oxidation are required, such as in aircraft gas turbines, combustion chambers, and automotive engine valves. The properties that make these materials suitable for these applications also make them difficult to grind. Grinding systems for such materials are often built around vitrified cBN (cubic boron nitride) wheels to realize maximum productivity and minimum cost per part. Conditions that yield the most economical combination of stock removal rate and wheel wear are key to the successful implementation of the grinding system. Identifying the transition point for excessive wheel wear is important. The aim of this study is to compare the performance of different cBN wheels when grinding difficult-to-grind (DTG) materials by determining the 'wheel wear characteristic curve', which correlates the G-ratio to the calculated tangential force per abrasive grain. With the proposed methodology, a threshold force per grit above which the wheel wear rate increases rapidly can be quickly identified. A comparison of performance for two abrasive product formulations in the grinding of three materials is presented. The obtained results can be applied for the development of grinding applications for DTG materials.

Abrasive wear study of white cast iron with different solidification rates

The abrasive wear resistance of white cast iron was studied. The iron was solidified using two solidification rates of 1.5 and 15 degrees C/s. Mass loss was evaluated with tests of the type pin on abrasive disc using alumina of different sizes. Two matrices were tested: one predominantly austenitic and the other predominantly martensitic, containing M(3)C carbides. Samples with cooling rate of 15 degrees C/s showed higher hardness and more refined microstructure compared with those solidified at 1.5 degrees C/s. During the test, the movement of successive abrasives gave rise to the strain hardening of the austenite phase, leading to the attainment of similar levels of surface hardness, which explains why the wear rate showed no difference compared to the austenite samples with different solidification rates. For the austenitic matrix the wear rate seems to depend on the hardness of the worn surface and not on the hardness of the material without deformation. The austenitic samples showed cracking and fracture of M(3)C carbides. For the predominantly martensitic matrix, the wear rate was higher at the solidification rate of 1.5 degrees C/s, for grain size of 66 and 93 mu m. Higher abrasive sizes were found to produce greater penetration and strain hardening of austenitic matrices. However, martensitic iron produces more microcutting, increasing the wear rate of the material. The analysis of the worn surface by scanning electron microscopy indicated abrasive wear mechanisms such as: microcutting, microfatigue and microploughing. Yet, for the iron of austenitic matrix, the microploughing mechanism was more severe. (C) 2009 Elsevier B.V. All rights reserved.

Mild and severe wear of steels and cast irons in sliding abrasion

This paper presents the results obtained in pin-on-disk test apparatus using glass and alumina as abrasive materials, showing the rates and mechanisms of abrasive wear of 1070 and 52100 steels, and ductile and white cast irons. The test conditions were selected in order to obtain wear rates that correspond to mild and severe abrasion, using different metal hardness-to-abrasive hardness ratios(H/H(A)) and 0.2 or 0.06 mm abrasive grains. The use of bulk Vickers hardness, instead of microhardness, allows a better description of the different abrasion regions. Under severe abrasion, the microcutting mechanism of wear prevailed together with friction coefficients larger than 0.4. On the other hand, when relatively soft abrasives are tested, indentation of abrasive particles followed by its fragmentation, and a creation of a thin deformed layer were the main damage mechanisms, with the friction coefficient lying below 0.4. The abrasive particle size under mild regime is able to change the wear rates in an order of magnitude. (C) 2009 Elsevier B.V. All rights reserved.

Loose abrasive truing and dressing of resin bond diamond cup wheels for grinding fibre optic connectors

A loose abrasive lapping technology was developed for truing and dressing ultrafine diamond cup wheels for grinding spherical end faces of fibre optic connectors. The relative densities of exposed grits and grit pull-outs measured from wheel surfaces prepared using the loose abrasive lapping and the bonded abrasive dressing were compared. It was found that the lapping method with loose abrasives produced wheel surfaces with more exposed grits and less grit pull-outs, especially for finer grit size wheels. For dressing ultrafine grit size wheels, the particle size of the lapping paste should be smaller than the wheel grit size to achieve a better result. It is also found that the wheels dressed using the lapping method demonstrate an excellent grinding performance. (C) 2004 Elsevier B.V.. All rights reserved.