Rick D. Wilson

Wear of titanium carbide reinforced metal matrix composites

Abstract The wear resistance of eight titanium carbide (TiC) reinforced metal matrix composites was investigated under different wear conditions. The TiC particles were dispersed in various steel and nickel matrices using a powder metallurgy (P/M) technique. Volume fraction of TiC particles in these composites varied between 0.35 and 0.45. The microstructure of each material was characterized using scanning electron microscopy (SEM), light optical microscopy, and X-ray diffraction (XRD). A high-stress abrasion test (pin abrasion), a low-stress abrasion test (dry-sand/rubber-wheel (DSRW)), an abrasion–impact test (impeller-in-drum) and an erosion test were utilized to understand the wear behavior of these materials under different conditions. While in the low-stress abrasion environment, finer TiC particles (with smaller interparticle spacing) provided better wear resistance, the coarser TiC particles were more effective in protecting the softer matrix from abrasion in the high-stress environment. On the other hand, variation in TiC size did not affect the rate of material loss in the impact–abrasion test. Erosion rate was unchanged with hardness of the composites.

Laboratory abrasive wear tests: investigation of test methods and alloy correlation

Abstract When screening materials, laboratory abrasive wear testing is a quick and inexpensive way of obtaining large quantities on information on wear rates and wear mechanisms. Typical laboratory abrasive wear tests approximate two- and three-body abrasion. The Albany Research Center, however, uses a suite of four laboratory abrasion, gouging–abrasion, and impact–gouging abrasion wear tests to rank materials for wear applications in the mining and minerals processing industries. These tests, and the wear mechanisms they approximate, are: (1) dry-sand, rubber-wheel (three-body, low-stress abrasion); (2) pin-on-drum (two-body, high-stress abrasion); (3) jaw crusher (high-stress gouging-abrasion); and (4) high-speed, impeller–tumbler (impact–abrasion). Subsequently, candidate materials can be ranked according to their performance for each of the wear tests. The abrasion, gouging–abrasion, and impact–abrasion test methods are described, highlighting the predominant wear mechanisms for each test. Data on a wide variety of irons and steels are presented with relative ranking of the materials according to the specific wear test.

A comparison of laboratory abrasion and field wear results

In the ongoing battle on wear, laboratory tests have been one tool used to evaluate and model the process of wear. A second, less commonly used tool is field wear testing. Field wear testing, while being more time-consuming, has the advantage that the materials are exposed to the actual environmental conditions and abrasives responsible for the wear loss. This paper examines four different abrasive wear tests (pin-on-drum, dry-sand rubber-wheel, jaw crusher, and impeller-in-drum), and compares the results obtained from these tests with field wear tests using the Albany Research Centers Planar Array Field wear test. A variety of ferrous-based alloys commonly used to resist abrasion in the mineral processing industry were tested, including carbon steels, low alloy steels, austenitic steels, and white cast iron.

Thermal sprayed titanium anode for cathodic protection of reinforced concrete bridges

Stable operation of cobalt catalyzed thermal sprayed titanium anodes for cathodic protection (CP) of bridge reinforcing steel was maintained in accelerated tests for a period equivalent to 23 years service at Oregon Department of Transportation (Oregon DOT) bridge CP conditions with no evidence that operation would degrade with further aging. The cobalt catalyst dispersed into the concrete near the anodeconcrete interface with electrochemical aging to produce a more diffuse anode reaction zone. The titanium anode had a porous heterogeneous structure composed of α-titanium containing interstitial oxygen and nitrogen, and a fee phase thought to be Ti(O,N). Splat cooling rates were 10 to 150 K/s, and microstructures were produced by equilibrium processes at the splat solidification front. Nitrogen gas atomization during thermal spraying produced a coating with more uniform composition, less cracking, and lower resistivity than using air atomization.

Impeller wear impact-abrasive wear test

Abstract In order to more accurately simulate wear behavior that occurs in the field (i.e., impact coupled with abrasion), an impeller-in-drum wear test has been developed. The apparatus is similar to the one first developed by Bond; however, in the apparatus used at the Albany Research Center, three paddles instead of just one are situated in the drum which can be impacted and abraded during the course of the wear test. In using three paddles, a standard can be run at the same time as the specimens of interest. Two test procedures have been developed which provide information on the relative resistance of a material to the combined action of impact and abrasion. In the first procedure, the wear samples are run for 1 h on each side of the specimen paddle. This average value of the two tests gives an upper average limit to the impact-abrasive wear of the material, but has the advantages of being easy to run and relatively quick. The second procedure attempts to determine the steady-state wear behavior by running sequential wear tests on one surface of the specimen paddle. In this procedure, anywhere from three to five 1-h tests are run on one surface of the paddle. The cumulative mass or volume loss is plotted as a function of time and the slope of the linear portion of the curve provides the value for the steady-state wear rate. In addition to describing the experimental procedure, wear mechanisms will be discussed and the changes that occur in the microstructure as a result of the wear tests will also be described. The way various alloys behave in pure abrasion and in impact–abrasion will be discussed, highlighting the change in a materials wear behavior with a change in wear mode.